This sounds like chassis flex is interfering with the physical click, I have experienced this and seen other posts like this Touchpad automatically depressing when chassis flexes.
That sounds like a different problem, have you tried disabling palm rejection or related settings like disable mouse while typing for testing?
Disabling PS/2 emulation in the BIOS was a suggested fix I saw in other similar threads but I don’t know if that will help.
I’m a little confused as to why you didn’t get a new input after the replacement was also not working? As long as the issue was present before your warranty expired or within 90 days of the replacement I would think you should be entitled to a replacement.
Have you contacted support recently?