[RiseofAsia]

this one first you need to have skills , electronics stuffs and experience repair phone before.
next sometime is just " hit and miss " come individual at home fixing phone. Partly you don't have those " standard machine " to Diagnostics on Your smart phone ". of course you can make it work but can last longer is another thing this is why I claim " hit and miss ' maybe lucky you make it work last longer maybe just work for one week break down again

This is why those repair shop offer min One month warranty after service.

Stabilizing issue is mainly due to data signal not stable.
Did the handphone repair shop, use oscilloscope to check all the important output signal waveforms especially power components  are functioning properly. If never provide this check, better dont let them repair.

SMT components are very small and easily drop off. A missing capacitor still not so bad, a missing resistor may make the handphone malfunction.