iPhone 4s having trouble charging and staying charged

Hello there guys!

So recently I noticed my iPhone 4s had the charge battery icon but was decreasing in percentage. Once it finally died, it had no life for about a day, trying different cables and from both a wall charger and different macbooks. Tried lots of resets, although I haven't actually tried a factory reset, but I really don't want to do that! Called Apple and they said it's possibly a hardware issue.

I then got some fluff and stuff out of the charging point of the iphone and sprayed some WD40 in the cable end and put it in and out trying to clean it. Kinda seemed to work and it actually started charging. But since then it's gone through stages of charging and not charging, staying off and staying on.

Now for example, it came on after charging, and usually it starts up with like 6/7% but this time it was just 1%, it climbed to 2%, then back down to 1% and then off but with the battery and thunderbolt screen. Now nothing again!

Just wondering if anyone's had any experience with this issue and could shed some light?

thankyou very much, Alex