'93 240SX battery draining / electrical wiring problem

[kayaker]

hi, folks:

my 240sx has been running great for the last 5 years, but starting this year, i am getting the electrical problem. first, the LED display for radio becomes flickering and then dead. now, the battery is draining out in about 5 hours. i am wondering if it is a common problem, and is it wiring or battery problem. the battery is 5 years old.

thanks for comments.

best.

z. li