I unplugged the MC12b for a few days due to lightning storms forecast. When I plugged it back in it would not come on. Stuck at diagnostics with ShSRAM_41 E:0300

The first step I would take is to unplug it and plug it back in, but I’m sure you’ve already done that. If there was a lightning strike while your screen was plugged in, and it just shut off, the internal electronics are most likely fried.
In the future, if you are aware of a storm happening, try to unplug all your electronics, and at the very least make sure they are plugged into a surge protector.

Motherboard fault. Contact the authorized service center.

during storms it is advisable to turn of and disconnect electronic devides, there must have been a strike not far from you?

Thunder storms can cause control boards to go erratic. Try unplugging the refrigerator for a minute or two and after plugging it back in hopefully the problem will go away.

Check the fuses on the power board. there is one fuse on primary side and one on secondary side.
Take of back panel and follow plug into the tv.where it ends is the power board.always use caution.the capacitors in there hold high voltage even after unplugged for a couple of days.Discharge capacitors before servicing the board.

Contact Harman Specialties thru their website
I used to work there

Unfortunately, this is what we call in the industry total meltdown due to merging circuitry. you will have to replace the entire circuit arrangement in this set. the audio ic's are probably the only components that are still operational. this repair will cost quite a bit to be honest. you may be better off purchasing a new set. sorry for the bad news there.

Good Day, gizmoally;

After storm to reset your TV; unplug TV from the wall for 4-6 minutes, then plug back into to wall, ensure outlet is working. If doesn't correct then TV's main a/c fuse may open.

Good Luck, big IRISH.

Good Day;

Two things normally happens after a L storm:1.) One must unplug TV for 5 minutes, then plug back in. 2.) Main glass fuse out, will be near a/c cord. 3.( Power regulator IC may be out. Try these first.

Good Luck!

Defective HV transformer. (Likely lost it during the storm)...accordianman