These chips can take a bit of time to erase fully when theyve been rewritten to a lot of times, so give it a heap of time erasing and then try it. .. They do eventually die though after a lot of erasures/rewrites.. Ive got a couple of dead ones laying around that wont erase or cant be written to any more..
Also I sometimes find that with my gq-4x(now that its a couple of years old and has been used heaps) can get a bad connection between the memcal adaptor pins and the burner socket, I just move the adaptor slightly from side to side in the burner socket, with the clamp slightly shut to put a slight pressure in the pins, and this cleans the contacts in the burner socket enough to get it working correctly again.. The socket must get some slight surface corrosion and this can be enough to stop it from getting a proper connection sometimes..