So bought a used 650 off ebay.

However, there seems to be a few problems with the keyboard. None of the buttons on the left side are working (q, a, options key, and the left button of the directional pad). And on the right side, O and L requires twice as much pressure than the other buttons in order for it to work.

But I've diagnosed the problem. Seems all the buttons work fine when I have the battery cover off. But once I put it back on, the buttons I mentioned earlier stop working. Not only that, but once the battery cover goes back on, the backlight starts to flicker and only comes on half of the time when I'm pressing any of the buttons, as opposed to staying on all the time with constant typing if I have the battery cover off.

Not sure how having a battery cover on would affect the phone. Have any of yall ever encountered a problem like this before? Have already tried a hard reset.