1. The 'NO RES' may be a hardware fault. I cannot help with that.
2. However it was also sometimes caused by a Firmware bug.
That can be fixed as follows,
It's a rather rare bug which first arose when the firmware was updated to 2107A and some later ones, with the receiver system date (year) being older than 2014. Or after update, the user sets by mistake a date (year) before 2014.
Fortunately there is a way for you to fix the problem, by forcing a new date (year) of at least 2014. It just takes 1 minute. Please proceed as follows:
The difficulty is that the receiver only accepts key presses at a specific time, which is only during 1 second right after the "plop" sound. There are 2 "plop" sounds which alternate, one lower pitch and one higher pitch. The higher pitch is the one to target as it allows a 1 second key press window.
F+3 to access the CLOCK settings page.
Press the down arrow to select the 4th line of the screen which shows the system date and time in the following format:
YY-MM-DD HH:MM
Followed by ENT which will fix the problem.