I have a similar issue.
On turning on the Minibrute, both envs are constantly triggered (both green LEDs lit) and if the sustain is above 0, I get a constant sound. There is also clear distortion/cracking in the audio path.
I've tried a new power supply which made no difference.
Also, when I power up the synth, roughly one in 10 times the env is ok, however the modulation section has no effect on the audio path.
So I get two scenarios:
1. always on env, but modulation ok
2. env behaves normally but no modulation
This is my 2nd Minibrute, and the second fault (returned first time for a tuning error).