I have three Raspberry Pis, all three with PoE hats. One of them works perfectly. The second one is completely non-functional. The third worked for about a day, then stopped working. All three are plugged in to the same Ubiquiti PoE switch (a UniFi Switch 8 POE-150W). The working Pi works on all ports. The non-working Pis don't work on any ports.
Could I really have two bad Pi hats out of three total? What else could be wrong with my setup that I can fix? Soldering anything is a non-starter - I have bad eyes and not nearly enough patience for that.
Update with info from a comment:
All three Pis will boot normally with an external power supply. The working one and one of the failing Pis are model 3 B+'s, the other failing Pi is a model 4. When I hook up the PoE cable, no lights come on and the Pis do not boot.