12C display not working

[Brianr88117]

Hello,

I am new to the forum and a complete beginner. I own a 12C which I purchased back in 2014. I used it for about a year then it went into my top drawer in its leather case, not to be used until recently. When I turned it on, the display hardly showed any numbers, but it was attempting to show me some. I changed the batteries to ones from a pack that I had in a drawer, but that yielded the same results.
Upon a serial number check this calculator was made in China in 2012, which doesn't seem that old compared to what I'm reading about the history of this calculator.
I tired the reset button located near the battery compartment, no change. I tried the (-) sign reset no change. I tried the paper clip to connect the + and -, and drain the capacitor, no channge. Before I purchase another 12C, I was hoping there was a way to fix this.
I did read that someone warmed up the screen connections from the inside, but I have no idea on how to open this up properly.
Any help would be appreciated.

[rprosperi]

Before you do anything else, I suggest you try it with new, good-quality CR2032 batteries; from your description, it sounds like the batteries may have been sitting around a while. When batteries are low, behavior of these machines is odd and nor easily predicted or consistent.

Remove both old batteries, short the terminals in the bay, press [ON] to bleed any residual charge in the board and let it sit empty until you get the new 2032 cells (but at least overnight).

Let us know how it goes.

[Maximilian Hohmann]

Hello!

And a (perhaps) stupid question from me: Did you try to increase the display contrast? The newer 12Cs, to my knowledge all models that are powered by CR2032 cells, have that function: press "f" together with "+" or "-" to change the contrast.

Regards
Max

[Mark H. Shin]

Welcome to the forum!

I'm afraid this condition seems to be a common affliction of the earlier releases of the new 12C with 2 CR2032 (S/N beginning with CNA; 4CY; and others).

It appears to be (in my humble opinion) a systemic flaw...

P.S. You can implement your mentioned heating method, without opening the unit, by simply placing the unit in the sunlight for some time, but it remains a very temporary fix at best...