How can a PMP 2000 be patched so that both internal amps are used to power the monitors, and the mains are sent from the mainpre-out to another power amp, while using one internal eq for the mains, and the other internal eq for the monitors, and using the internal effects for both the mains and the monitors?

On the back panel there is a section labelled Patch Bay
There are 2 small switches which assign each Power Amp to either Monitor or Main Output.
It would seem you have them both set the same at present. Set one to Monitor and one to Main, and use the corresponding Power Amp outputs direct to speakers.

Note you can send signal to external amps or powered speakers from the preamp outputs. This is really handy.
Download and print the manual from https://www.manualslib.com/manual/90516/Kustom-Kpm-8420t.html
and keep it with the mixer.

( Of course don't send speaker outputs to other amps or powered speakers )

I'd need to know what mixer you have, to know if there is a [line out] connection socket and an [internal amp in] connection socket.

"each with own poweramp" I presume means the ep1500's and NOT that the speakers are active (ie containing amps)

***If any of your speakers are active, ask the question again, with more detail.***

So if all your speakers are passive, I offer the following.

I assume there is [effect send] and [effect return] on the mixer

effect send>quadraverb>effect return

mixer line out > eq > compressor > sonic maximizer > crossover

sub output of crossover> amp > sub
high output of crossover to mixer's internal amp input
mixer's speaker output > main speakers

monitor output > other side of eq (>other side of compressor if desired, but use sparingly ) > other side of sonic max if it is true stereo , otherwise skip > amp > monitors

If your mixer doesn't have an input to its internal amp, we are "back to the drawing board"
With questions like this it pays to give as much detail as possible; model and make of each component etc
I have done my best with the the info you have provided.
Don't feed amp outputs into powered speakers

Yes, you blew out components associated with the monitor sends. There are several components including an RF bypass to ground and the driver IC, IC8 and a decoupling electrolytic cap. The repair is going to be extensive as it is likely you will have to remove ALL the panel knobs and screws to free up the circuit board for repair. I have worked on several mixers and have three of the PMP5000's myself and dread removing the main board. I am going to suggest something you might consider: Many of the PMP's fail either in their power supply or one of the amps. Due to the repair cost I would consider getting a scrap PMP with this problem and swapping out the panelboard for yours. Often you can get one with blown supply or power amp for around $200 and I suspect a repair shop is going to charge at least that to repair your unit... Then you will have a spare parts bucket as well.

Plug a balanced TRS (tip ring sleeve) cable into either main or monitor 1/4 inch jacks and then into the amp. ALWAYS use balanced lines AND power the mixer AND the amps from the SAME receptacle to avoid damage from ground loop bounce,

Bridge mode you use chan B (left connector on the back) using a SPECIALLY wired Speakon. The impedance of a speaker connected as such CANNOT be LESS than 8 ohms.

In the Main/Mon mode, the two amplifiers are separated in function. The monitor knobs for EACH channel input control the mix sent to Channel A which is for the monitor speakers. The Mon1 controls the level sent to Output A for the monitor speakers. Mon2 fader is NOT used.

The individual channel faders control the main mix and the Main fader controls the level sent to Output B which goes to the main speakers.

If the fuse has blown DO NOT replace it without repairing the cause of the failure. You will likely do more damage to internal components. Take the unit for repair before applying power again. I have repaired many of these and first a failure occurs in one of the power amps... usually the A channel, then people replace a fuse that protected the power supply and that blows the power supply taking out another $30 of components and $200 labor. (they are hard to change) If the unit is under warranty, exercise your warranty immediately. There is a weak spot in the channel A power amp.

ALSO please read my tip on here about a hazard in PMP series powered mixers. It is in regard to using Speakon to 1/4 inch speaker cables... NOTE that the BARREL of a 1/4 inch speaker cable or adapter from the Speakon is the HOT side for channel A and if you ground it inadvertenly, goodbye channel A power amp!!!

The MON faders ONLY control the output to the MON L and MON R jacks, NOT the split use of MAIN/MON outputs. You MIGHT try varying the MONO fader and see if it varies the MON part of the split output.
Best to use the unit as MAIN L and R to main speakers and use a stereo amp or POWERED monitors driven from the MON L and R jacks. With this, the MON faders will control your monitors as you would like them to.
ALSO make sure ALL equipment connected together is powered from teh same recepacle power system. Powering interconnected equipment from receptacles at opposite ends of the room is asking for damage due to ground bounce and faults.
PLEASE read my tip on here about a HAZARD of speaker polarity if you use Speakon to 1/4 inch cables.

Please read a tip I just posted regarding a hazard of the Speakon to 1/4 inch cables when used with these PMP mixers.

If you are using your main speakers as stereo, then you will need either powered monitor speakers OR an additional seperate amp for them. The mon outputs on the mixer are LINE LEVEL and are not driven by a power amp. Use TRS (balanced) interconnect cables from these to POWERED monitor speakers.

You can parallel your two mains providing the parallel impedance is 4 ohms or greater (two 8 ohms in parallel at most). The the monitor speakers can be paralleled and the switch set to Main/Mon so that one side of the power amp drives the mains and the other drives the monitors.

To prevent damage to the mixer, make sure all speaker leads are secure before powering the system. Run the speaker leads through the handles of the speakers to prevent inadvertent unplugging due to personell tripping over cables.

DO NOT use the bridge mode in your use.

Better way... Connect the main speakers via the Speakons and then put a Power Subwoofer to one of the Monitor connections IF you are not using both stage monitors. If you need to kill the lows to the mains, use the EQ in the PMP-3000.

Use the EQ that is USUALLY on the subwoofer to kill the highs to the sub.

Lot less cables and hardware.

REMEMBER for equipment safety, power ALL interconnected equipment from the same source be it a receptacle or power distribution system.

Powering parts of a system from receptacles strewn around a room is asking for trouble of ground loops and ground faults.

Assuming you are using BOTH power channels for your main speakers, you MUST use external, additional, amplifiers for the monitors. There are ONLY two power amps in the PMP5000.

The other option is to run mono for the mains and use the second power amp (comes out on the Speakon connectors) to drive the monitors. For this, the little slide switch has to be on the middle position.

Doing this, you have to adjust the monitor volume controls for each strip.