Wont turn on

could be a power saving feature check your manual

Have you checked fuses? You may have overloaded the amp and caused a fault internally. I have experienced power supply faults with Mackie products, but it may be a simple fix. Find a local repairer to have a look at it.

Make sure the batteries are all facing the same and the correct direction.

I have the same problem except mine worked out of the blue then stop after a minute whilst mixing, m-audio/avid are no help what so ever, as they want me to pay to speak to a support advisor.

Exercise your warranty. There is a problem, likely with the power supply regulator going into overheat shutdown mode.

Try headphones... possibly the switch contacts on the headphone jack which disconnect the speaker when headpones are plugged in. If you can hear via the headphones, check the switch contacts. Also look for a loose cable.

Contacts can oxidize when idle for a long time.

The unit will require repair and if you are not adept at electronics, you will need to take it to a shop. Likely there is failure in the power supply or amplifier that has blown the fuse. Replacing the fuse WITHOUT repairing the cause MAY do additional damage.

Usuaully when a tuner flashes, it means it is on and hasn't received any signal for awhile. Your pickup may be bad or disconnected. Are you able to get any output from the guitar?

Sounds like a power supply problem. Likely have to go to a repair shop unless you are electronically capable.

I would expect either a cracked board or bad solder joint is causing the problem.

If you can solder, try resoldering any connections on the board that appear grainy or have rings. It is likely that after the unit has been working for a while, the heat is causing a marginal connection to open up.

Keep us posted.

Dan