I have a foldable 120w one with 4 panels in sewn cloth. Gust blew it and the little plastic anti-tug box broke so wires could move.
Still worked, but one day the watts were halved.
Examined wires closely, not easy because most of that little protective box still in place, but it looked like they twisted around each other in there, so I untwisted and glued anti-tug fitting to case so it can't turn again.
Today broke two mounts of the little box so I can see wires clearly, two stranded leads with what looks like a can cap in between and the remains of a foam strip that looks like it went in between.
Still puts out half wattage at about 24v, but I'm wondering if wires under the fabric case are disconnected. It used to put out more than the rated 120w, I've seen 138w on the battery boxes meter.
My thinking is either open the case seam to see in, or assume a panel or two shorted and are lost anyway, leave alone and be happy it works at all.
One thing I don't know what happens when solar panels short, if that's what happened. I do have a DVM and could check resistance, but without disassembly it would be cumulative.
Or the twisting could have disconnected one or more panels, they're supposedly wired in series and its putting out like it would on an overcast day. In which case I might be able to reconnect them.
Bluetti is nice enough superficially but I'm sure I'm unlikely to get tech info out of them. They're very Apple-like is dealing with consumers.
(BTW, they will sell your email address to multiple marketers promoting "sales" of bluetti products after a purchase. Not a lot, but the sender addresses are always different.)
Thank you.