It is very hard to detach the connector with the spudger. I tried forcing the connector out with the spudger by pushing on one side and then the other repeatedly. After several times it finally came out. A tool would be useful for this; there must be special plyers for doing this. Fingernails on either side seems most obvious, but maybe there is a downside to this ?

I used a microfiber cloth instead, which worked well. The same type as yo use to clean eye glasses, but in a larger form factor.

Rather old post, but anyhow, I have the same situation now. Will reinstall the old battery again to see if it is a battery issue or a broken circuitboard issue. How did it work out for you?

To install the battery it is not true that you do exactly the reverse.

One thing I struggled with was getting the battery connector back on. The trick I saw later on a video was to:

- First attach the connector, and after that

- Place the battery in the phone

The advantage of this is that the flat cable does not "work against" the connector when trying to click it back on. Would have saved me quiet some time.