Some people have been having problems with the IRDA modules on their Sendo X phones, which in turn causes rapid battery discharge and a heating up of the handset. This is caused by a known bug in the 18.104.22.168 firmware.
There's currently NO fix for this, so please be patient. We know the problems exist, but Sendo are no longer, and so we have no access to source files! Please do not send repeated emails or post in the forum about this!