Raspberry Pi power LED blinking

Hi, i have this Raspberry pi 4 2GB since 2020 and few months ago the pi randomly shut off and wouldn't work after that. I tried searching it online (I found that it is some problem with power like short or the power chip failed) after that I didn't want to deal with it at the moment soo i kinda forgot about it. But now i kinda want it to work, could someone help me? Here's what i kinda got from it: When i plug it with the offical rpi brick it just blinks red I tried switching power bricks, i tried my phone charger (which can do 5V 3A) and for some reason the blinks are more dimmed and less frequent. I include videos of the blinks on the offical brick and my (the black cable is the offical) Anyone know how to fix it?

If the red light on your Raspberry Pi is continuous, it indicates that your device is getting enough power to power on safely and should be performing correctly. Do you use a power supply that meets the official specs, see the faq section for advice.

Yes, On the first video I'm using offical Raspberry pi 4 power supply and on the second video i tried my phone charcher which can also do 5V 3A (what rpi 4 needs)

Even if the charger can deliver the power sometimes underspecced USB cable can be the culprit.

Okey, I have 100% good cable i use it for fast carching phone with 30W no problem.. but it just blinks even with the offical power supply... so ?

Reinstall OS or install newer OS

Measure the 5v with a multimeter. Because the Raspberry Pi 4s diagnostic is indicating a to low voltage on the input by blinking the red LED! So either is the 5v to low or the diagnostic is wrong and the Raspberry Pi 4 is faulty.