I did noticed that it have severe light bleeding (which it did not had previously) from the top (all of the top) so probably mishandled when i was not at home and busy at the university.
If that's the case then the monitor should not even power up? or should take a long time to power up? I dont know, this is a really old and kinda overused monitor and the only rest it has is when i tucked it away when i went to university. only to turn it on after 2 ~ 3 years.
I kept the monitor powered for an entire day and then connected it to the system and it still took 10 ~ 15 mins to show anything. Then after a few mins i decided to restart the computer and Bam again took 15 mins to get the signal and show anything on screen although it was powered on all this time and only thing i did is restart the computer.
Basically, a monitor has three* parts. A PSU board, a logic board, and the LCD itself.
*This assumes you count the back-light as part of the LCD, even though it's technically not, and count the little control board with the buttons as part of the logic board, which it plugs into but is usually not physically a part of. Maybe instead of "parts" I should say "major subsystems."
PSUs are prone to capacitor degradation and can cause a lot of weird "wonky monitor" problems, like not always turning on, turning off for no apparent reason, etc. Because of the big capacitors used to convert AC to DC power, and because of cheap manufacturers, they're the source of probably 90+% of "wonky monitor" issues.
But to me, what you're describing (full blast backlighting, auto-sense failures, etc.) sounds a lot more like a bad logic board. Fortunately, you can probably find a replacement for way less than the cost of a new monitor - I usually start with shopjimmy because they're local to me (so shipping is fast) or, you know, eBay. Actually swapping it will probably be a piece of cake.
That assumes the parts are cheaper than a new monitor. (If you get lucky on a sale or get something that's a factory refurb, you can get a ~21" 1080p display for like $100.)
Good luck.