Problems battery replacement. Problems with battery power cable?

I tried replacing the battery of my Macbook Pro but had some issues. The most pressing of which is that the pancake screw of the battery power cable broke. Half of it is in the hole, and the other half, the head, is broken off. Taping it together in various ways did give some various results:

• startup but no battery recognized. It only works plugged in. Sometimes with the fan at max speed even though the laptop is cold.
• No startup at all
• Startup and the battery is recognized at 100% and works without charger. This stopped working after about 5 minutes and then went to scenario 2 again. But this at least shows the battery is working I guess.

It would make sense this is all caused by the power cable not making contact. But in some of the instances when opening up the laptop again the battery data cable also seemed to be loose. So my first question is if any of these scenarios indicate more issues than just the battery power cable. Should I replace the data cable?

Next question: what should I do with the power contact? Glue down the battery power cable? Would this guarantee enough contact or does it need to be bolted down by a screw?

I think I explained everything that happened but let me know if I can clarify things, perhaps with pictures.