Sorry you have had so much trouble up til this point @RaymondTheBrave
As to your notion of a common starting point for troubleshooting - we do have those.
They usually include commands such as inxi - ‘command line system information tool for console…’;
inxi -Farz
And guides that expound on those methods as well as outline other things like how to format code in the forum like this this one;
To your issue
combined with the previous steps and outcomes leads me to believe there may be conflicting/compounding issues - the *meta packages, various kernels, and as any yet unidentified problems with the system packages, support of the device under different kernels, and the state of different kernels in the different branches.
Let us first print all installed kernels;
pacman -Qsq '^linux[0-9][0-9]?[0-9]$'
Similarly let us double check on any linux-meta packages;
pacman -Qsq 'linux-meta|linux-lts-meta'