If stuck on "Locating Network Services" then can not find your network (configured ssid) for the configured 802.11 mode. If occuring on multiple phones, then must be a configuration issue and not hardware issue.
For the battery issue, is it standard or extended battery?
The odd thing about the 7921 issue is device will register and appear to look and work fine, then revert to locating network services, then repeats cycle. Seems like after sitting idle (on or off the charger)or like after phone warms up, it reverts to locating network services. At that time there is no radio signal and CCM shows device as not registered.
Have reset devices to factory default setting and reconfigured, but same end result.
We have about 15 7921's with this issue and do not use them since they're not fully functional.
Symbol AP is not a supported platform. If the beacon does not come at the correct time, then the client can miss it and deem BSS loss. Also if sending data frames, the AP must ACK those frams as well. If not the client can claim BSS loss. You may want to check with Symbol. I know there were some udpates also in regards to supporting power save clients. The 7921G should use PS-POLL there as I don't think that AP supports U-APSD or WMM.