Voice remote pro not holding charge

I have been enjoying my Voice Remote Pro (RC538) since I was invited to purchase it via the Early Access Program back in Feb 2021. The remote has worked flawlessly since then, but recently it will not charge above 13% and as soon as I unplug it from the charger, the charge level begins dropping rapidly (for example, falling to 8% within a minute).

I've tried different combinations of 4 different USB wall adapters and 4 different USB cords (including the one that came with the remote) at different outlets throughout the house, but even though I see the "Remote Charging" indicator on-screen and the slowly blinking green light on the back, it never charges above 13% (even when left plugged in for several days straight). I also tried to re-start the remote and re-pair it with my Roku TV (based on suggestions I saw in these forums from Roku from support staff) - that works and the remote functions as normal, but the rechargeable battery drains really quickly and won't ever charge above 13%. 

I bought this thinking it would be a greener solution than a typical remote, but if the crummy battery they shipped it with can't last more than two years (and I'd now have to replace the entire thing rather than just swap in new batteries) that sort of blows up the whole idea.