Okay, I think I found the RUU exe file for my device. But I have this problem where it just stuck at Updating... (1/1) Sending...
I'm the RUU file - RUU_M8_UL_M60_SENSE70_ATT_MR_Cingular_US_6.20.502.5_combined. I don't know if I need to be in Unlock/Lock/Relock state of bootloader.
modelid: 0P6B12000
cidnum: CWS__001
Correct bootloader state to install RUU would be locked or relocked (unless you have s-off, in which case any bootloader condition will work).
Since the RUU is stuck updating, I believe this usually means that security checks (bootloader locked, MID and CID check, etc.) are already passed. The RUU simply got stuck. If you haven't already done so, it should typically be okay to disconnect the phone, kill the process, etc. and start over again. A lot of times, simply trying the RUU again, will do that trick.
Otherwise, you may need to try another USB port on your PC, another cable, or even another PC. RUU can be quite finicky with the PC setup. It also
must be a real PC (not emulated Mac, etc.).
If you also know how, please do fastboot getvar all, and post the output (delete IMEI and serial number before posting) so we can see the details on your phone. In some circumstances, how you determined the MID and CID may not actually be getting reported correctly (you didn't mention how you determined these, getvar all is the best and most accurate way).