Our Samsung Dishwasher model DMS300TRS will not power up. have checked all connections and sockets and all is OK.

bad light socket?....
https://www.partselect.com/AdvancedModelSearch.aspx?ModelNum=EV190NXRW1&mfgModelNum=&fkMfgID=3
not sure the model as there are 12 ev190n****

Check wiring with a test light or volt meter. switch lights to low beam, connect volt meter N probe to a good ground then probe the light socket for the low beam power cable, should show battery voltage, now switch to high beam and test for battery voltage if ok remove the grounded meter probe and probe the cable in the socket that you have not tested this is the ground cable, battery voltage should show if ground cable is ok. If no voltage repair cable ,If voltage present check filament on bulb high beam perhaps the new bulb is faulty.

When you connect the power adapter into the laptop, does the power LED light up? If not then - The battery adapter or the adapter's power lead or the laptop's power socket could be faulty. Check power adapter's DC plug that connects into the laptop power socket with a multi-meter, the voltage should be slightly higher than the voltage that is printed on the label on the bottom of the adapter. If the voltage is zero or way below the voltage that is printed on the label then the power adapter is faulty and needs to be replaced. If the adapter is OK then connect it to the laptop and power it up, then look at the power/battery charging LED light and wriggle the power plug in the laptop's power socket. If the power/battery LED light flashes and in a certain position this LED light stays firm, then the power socket is either faulty or it has a dry solder joint where it is connected to the motherboard. This can be repaired but it requires the laptop to be completely dismantled to get at this power socket and repair. If you cannot DIY then I suggest you get a quote first.

When you connect the power adapter into the laptop, does the power LED light up? If not then - The battery adapter or the adapter's power lead or the laptop's power socket could be faulty. Check power adapter's DC plug that connects into the laptop power socket with a multi-meter, the voltage should be slightly higher than the voltage that is printed on the label on the bottom of the adapter. If the voltage is zero or way below the voltage that is printed on the label then the power adapter is faulty and needs to be replaced. If the adapter is OK then connect it to the laptop and power it up, then look at the power/battery charging LED light and wriggle the power plug in the laptop's power socket. If the power/battery LED light flashes and in a certain position this LED light stays firm, then the power socket is either faulty or it has a dry solder joint where it is connected to the motherboard. This can be repaired but it requires the laptop to be completely dismantled to get at this power socket and repair. If you cannot DIY then I suggest you get a quote first.

When you connect the power adapter into the laptop, does the power LED light up? If not then - The battery adapter or the adapter's power lead or the laptop's power socket could be faulty. Check power adapter's DC plug that connects into the laptop power socket with a multi-meter, the voltage should be slightly higher than the voltage that is printed on the label on the bottom of the adapter. If the voltage is zero or way below the voltage that is printed on the label then the power adapter is faulty and needs to be replaced. If the adapter is OK then connect it to the laptop and power it up, then look at the power/battery charging LED light and wriggle the power plug in the laptop's power socket. If the power/battery LED light flashes and in a certain position this LED light stays firm, then the power socket is either faulty or it has a dry solder joint where it is connected to the motherboard. This can be repaired but it requires the laptop to be completely dismantled to get at this power socket and repair. If you cannot DIY then I suggest you get a quote first.

Have the same problem with brand new, unused DMS500TR dishwasher. Rang Samsung, they said F3 is a water leak error.

You say "electrical installation checked OK"...is the machine hard wired into a junction box or does it plug into an outlet?

If in a wall socket the new house circut may be on a wall switch which is currently off. If it is plugged into a GFI outlet it may have tripped, Find another power source to wire to, GFI plugs and dishmachines just don't get along, Learned that some time ago!

There may be an issue with your door safety switch on the unit.

Check for voltage where the house wires are wire capped in the machine if hard wired, sometimes twisting those can cause issues.

I doubt your machine has a reset switch but many hobart units have on on the motors.

It really sounds like you have a voltage issue.

Have you determined the problem correctly?
The fault maybe the power adapter or the power plug that connects into the laptop's power socket rather than the power socket on the laptop.

Check power adapter’s DC plug that connects into the laptop power socket with a multi-meter, the voltage should be slightly higher than the voltage that is printed on the label on the bottom of the adapter. If the voltage is zero or way below the voltage that is printed on the label then the power adapter is faulty and needs to be replaced.
If the adapter is OK then connect it to the laptop and power it up, then look at the power/battery charging LED light and wriggle the power plug in the laptop's power socket. If the power/battery LED light flashes and in a certain position this LED light stays firm, then the power socket is either faulty or it has a dry solder joint where it is connected to the motherboard.
This can be repaired but it requires the laptop to be completely dismantled to get at this power socket and repair. The power socket is soldered directly onto the motherboard, there is no wiring required.
If you cannot DIY then I suggest you get a quote first.

check connection at connection box under dishwasher behind lower pannel was ther power to the switch some dishwashers have a thermal fuse in the console white plastic whith two wires going to it

check the connections to the sensors inside of te evaporator compartmnet to the freezer. the fan won't come on untill the evsaporator temperayture is 0 degrees. hAVE YOU CLEANED OUT THE CONDENSER IN THE BACK LATELY? it may be dirty.