Copper dot inside battery compartment below the SIM and MEM mount

There is a copper dot inside the battery compartment just below the sim and memory. It looks like a ground pad for testing, to me .

What is it ?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0