Hi All,
Just thought I would let people know it is possible to do a hard reset of the EM-406A, but it is not the easiest process. You need to unsolder all the edges of the metal case. Remove the corner pice that is on the opposite side to the antenna.
You should see a pin coming through a through plate hole. Unsloder his and pull the antenna and metal casing off the other side. This will reveal a small battery in one corner. This cannot easily be removed so unsolder and resolder one of its terminals to perform a reboot. Then re-assemble and it should work.
Certainly fixed an issue with mine where the comms became undesiferable.
I can’t comment on warrantee issues on this, but if you can’t get a replacement like me, then this might be your only option.