After 2 weeks vacation keyless remote stopped working suddenly: honda civic ex 1998 2drs! why ???

Dear Experts,
I have a Honda Civic EX 1998 2DR with a factory remote keyless and factory AM/FM receiver and factory CD player.
Problem: After 2 weeks I came back from a vacation (nobody drove the car). The keyless remote stopped working. Nobody dropped it.
I replaced the keyless remote batery. The same effect - no functionality. Tried to re-program the keyless remote - no result, no functionality, the car doesn't see the keyless remote even during the re-programming. I cheked the fuse for the keyless entry/cruise control.
It is OK. The cruise control works fine.
1) My friend who looked after my car while I was away told me that once in the night he noticed that the interior overhead light was flickering. He switched it to the "OFF" postion (he had a regular metal key). 2) The charge of the car battery became weaker (probably as a result of
that light flickering). 3) The car starts wells, runs well, the interior overhead light works fine when I close/open the doors, no flickering, AM/FM is fully functional, CD is ok.
I read in the forum that the keyless remote unit is built into the the standard receiver head unit and it is also responsible for that overhead light.
1) What might be the cause? Does the AM/FM receiver have a blown circuit for the keyless remote? 2) Do I use the right reprogramming instructions: doors unlocked, ignition on, lock or unlock button .... ? I have honda civic ex, 1998, 2drs. My manual refers me to the dealership for the re-programming. I encountered somewhere on the web that for some honda civics you have to hold a button between AM/FM and CD/tape and do something with the keyless remote at the same time. I can't find this again. 3) Any other ways to determine the cause of the problem?
P.S. I completly trust my friend - anyway the mileage was the same.
I don't feel like paying hundred bucks for a stupid diagnostic at the dealership if the problem is at the surface. I'm sure someone had a similar problem.
Thanks, Max.
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