Another thought: Since that user "petrel-p1" in serial console of stock fw has root previlege, maybe I can compile a Linux executable to play with efuse there.
If the efuse can be written again, I can write secure boot control bit 0 to disable it.
Hi, usually the e-fuse is OTP type ("Electrical Fuse, A one-time programmable memory"), can be write only once. I don't have the documentation of that Allwinner SOC, is not impossible to be in this case is something different, but usually this is the way how the e-fuse works.