TI-82 STATS does not power up properly anymore.

[Refrigerator]

My precious TI-82 has been having problems powering up for about a year now, it would take a few tries to get it running and sometimes it would even display "MEM CLEARED", after one good power up it turns on without problems if i don't leave it off for too long.
Also most of the time after a difficult power on it has the contrast way up so i have to re-adjust it
But now i pulled it out to do some TL431 resistor divider calculations and it doesn't power up anymore 
Has anyone had this happen? Could it be a simple fix?
BTW, the batteries are good.

PS: while writing this post i gave it another try and it powered up and the contrast is way up as well.

[shakalnokturn]

...
BTW, the batteries are good.
...

This may sound a stupid question of course: You have checked the backup battery too?
Otherwise check PCB for battery corrosion.

[Refrigerator]

I had it replaced before the other one went bad but i figured it wouldn't hurt but the next day i had a "MEM CLEARED" and i knew it had nothing to do with the batteries.
The one buttoncell that i replaced was still like new so i keep it in the battery tray as a spare.