I figured out how to fix mine by comparing it to my normal Beylauncher, and have managed to do it again three times since from memory, but I wouldn't recommend trying to do it that way
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They're not easy to fix unless you're used to doing that kinda thing (I've done a fair bit of electrical/amp/soldering work). But what will have happened is that the metal spring will have slipped out of place and not be properly anchored. You'd need to open it up, try to prevent the spring going everywhere, and set it back up, then re-wind it... I'm sure you saw that on youtube though. It's quite fiddly as once wound, if you let go, they unwind again, so you have to put it all together really fast.
Ugh, I just wish TT would release that single beylauncher LR already, I'm gonna buy a couple when they do.
One suggestion, if you used a beylauncher LR fixing video, the break is the same as a normal beylauncher, so for the spring part, use a normal beylauncher video, and for the reassembly use the LR video (though you have to reassemble quickly).