Calculator wont turn on

ti83 plus power board contacts wear out. take the calc apart and put a layer of solder on it.

Hello I need help!!! My TI-83 Plus after changing the batteries and the internal battery, is still giving me a problem.. When I power it on all I see is one horizontal line at the bottom and then it starts to fade and I see nothing at all.

I fix calculators. Usually the power contact corrodes inside the case. And screen flex cables corrode. Ill post a fix sometime, otherwise there r online guides. No power problems cant be diagnosed with a tester. Open it up

What if I was getting data from another calculator but at the end my didn't want to turn on

I have a problem with my calculator except that its from a different company and a lot older. Its the Casio fx-991W and i found it just now and it ain't working and when i checked the back, it had no batteries but there is a way, we can turn it on even without batteries. Would anyone help me on this one?