PSVita charges for a bit then stops

Hello everyone, I've been trying to fix this for weeks and now is the time to ask some experts.

I bought a used PSVita a month ago or so, the seller said everything was okay so I thought no problem.

When I first tried to power it on, it didn't so I figured it was discharged, so I put the charger on and the orange light was blinking, so far so good. After awhile the orange stopped blinking and I tried to power it on, it worked, everything was functional, screen, rear pad etc, there was an issue tho, the battery just charged enough to turn on so I put the charger again and it didn't charge while the PSVita was on, so I turned it off and did the same. The orange light once again turned on but instead of blinking, it was solid orange, but…just for 20/30 seconds or so, then it turned off, I connected the charger again and it charges again for a bit and then stops.

My thought solutions:

• Open the Vita and disconnect the battery for some minutes - Did this multiple times and only once I got results, I connected the battery again and put it charging right away, it would charge for a long time, I mean 5 hours plus and when I tried to turn it on, only had half battery, if I tried to keep charging it after turning it off, once again did the 20/30 sec charging then stops.
• Buying a new PSVita battery - The battery was full charged and the PSVita was working perfectly, I let it discharge before trying to charge but guess what, the battery wasn't the problem because the problem was the same.
• Connecting the charger cable to a 5V 2A charger - didn't work.
• Cleaning the inside motherboard, components and connectors - Did so with compressed air and cleaned every bit of dust, didn't work.
• Buying a new charger cable - The cable seems to have some missing pins and if I move it too much, it stops charging right away, the whole charger isn't original neither, I already ordered a new charger cable and I'm hoping it will work.
• The charging port is damaged - I really hope this isn't the issue because I don't have soldering skills.

Any kind of help and advice is welcome, I have a toolkit and professional formation in dealing with electronic components and opening etc, but anything dealing with soldering is not for me.

Thanks in advance.