System 80 alarm?

[Retropin]

My Spiderman has taken to having what sounds like an alarm sound being made continuously... the game still plays but it has this Da- Da..Da-Da noise all the time. Sounds like a warning noise which of course ive done my best to ignore.
Also racks up credits OK but wipes all at the push of the start button.
1 or more of the displays will show all segments lit pretty brightly.

All grounding mods and then some have been done, ive also brigded the traces for the door slam switch..

... any clues???

[Marty Machine]

I was about to suggest a possible stuck-switch on the playfield somewhere, but the "bright score" might suggest an incorrect voltage somewhere which is also causing some other logic fault and hence the sound you hear????

Anyone???

[The pinballist formally known as Dean Morgan]

Connectors, have you tried reseating them?