I hope that you can fix that through recovery mode, but I suspect its a busted CPU (not GPU). Since Slim PS3 are notorious for having breaking CPU's and reball wont fix it, replacing CPU is not an option since its paired with motherboard.
it run ofw 4.11 and have long time standby (like 2 month) the other day just want to play a little and ps3 does this thing. probably i need to solder tristate with gnd, for you to know i do the fan test and it go ok. thx for reply
nothing good may happen on touching the flash of your PS3 when you left your console for 2 months doing nothing. I suspect that it's a broken PSU, who knows it might be damage when you left your console plugged it for 2 months where the event happens that electrical spike occurred.