Thanks for the information: by adjusting the timing between the two presses of “menu” I could indeed get into the test menu. 00 then showed “sw: 2.0”.
Great to hear although it did not solve your problem.
If you end up looking for another BL3500 with the correct software the best chance might be a MK2, although they came with software 3.0 or 3.1 initially so no garantee for the correct SW version
.
.