Common eBike problems and solutions

Hey everyone!

Been lurking for a bit and finally decided to jump in. I'm building out a custom hardtail eMTB – Bafang BBSHD, 52V battery, planning for some serious trail riding and commuting. I'm curious, for those of you who've gone the custom build route, what are some of the most common issues you've run into, either during the build or after hitting the trails? Things like wiring gremlins, motor overheating, chainline woes, or even just unexpected component failures. And more importantly, what clever solutions did you come up with? Share your war stories and wisdom!