I‘ve attempted to have 2x hardware repairs (1x battery on my phone, 1x cracked screen on my wife’s) whilst on dev betas and were told on both occasions I had to downgrade first. Other’s in this thread have had the same experience.First of all, I've gotten my phone serviced before on a beta, and they told me it doesn't matter because it's a hardware issue (which a degraded battery would fall under that category). Second, it's not like they're going to replace a battery based on a screenshot from the beta I'm on. They're going to run their own tests on their own network. Worse comes to worse, I'll downgrade hoping it shows the same percentage.
Good luck!