Problems with bk 9918

[Serum]

I don't know if it caused permanent damage. did you drove it before on 14 cells? (without this glitching?)

Yes, you should use the UBEC, it is likely it doesn't glitch anymore when you use the UBEC. (ubec rules, it is a more stable supply for the receiver than the BEC on the 9918)

Did you checked the BEC jumper? (did you find it? ;) )