Have you tried using another charging source?
Some powerbanks will auto-cutoff moments after you connect and will result in the unit draining instead of charging. You need to find a steady USB power source or a powerbank that works.
I posted about that before. originally i was trying to charge with a powerbank, but quickly realized it wasn't working. So yes, i've been using a wall socket with different high quality usb chargers and so on, i'm confident the issue is with the group / RD and not the juice. Also, i've handled 5 groups, i have 4 at home currently, so i know what works and doesn't, what should work but doesn't, and so on.
Ltwoo has asked if i have ridden in the rain, so presumably the charging issue has been linked to water exposure, which could explain why the new version has a USB C port in the FD. I'm speculating, because they're not exactly forthcoming w info, but it's the first time they ask a question.
For those with garmin devices, you can link the er9/erx w your head unit. tells you the level of charge of the battery, as well as which gear you're in, it's very neat.