Galaxy m51 not charging

I have my m51 for over 3 years already, dropped it so many times (cracked like 3 screen protectors), no problems until this year.

Now it was not charging, i tried cleaning the port, any other method that doesn't involve opening up the phone and as a last resort I tried hitting it (stupid idea ik) and after that it charged. After that I've got this problem again a lot of times, hitting it worked.

Now hitting doesn't work, I opened the phone up (first time ever btw), i carefully opened and separated everything until i could see the 2 boards. Carefully inspected both, no sign of damage or anything . Main board flex seems to be fine.

Should i replace both the charging board and the main flex or just the board.

And also before opening phone up i had a problem where the phone was on and screen wasn't showing anything, as always slapping it worked (dont tell me it was the slapping, everything inside looked in perfect condition no damage, at least to my eye).

If fixing it would include micro soldering or anything more expensive than 50$ im just getting a new phone.