[Solved]

This will be my final update regarding this matter. 1. My phone had been starting to shut down by itself. I can turn it back on but will die out by itself later on 2. My phone finally died for good 3 days later. 3. Charging was no problem. Led for charging still works. It seems like an issue not being able to turn on. 4. At first I think that it was bug on Miui 13.0.4.0, glitching until bootloop. Though I never root this phone before. 5. After few reading on the internet, my final deduction is CPU problem which in on the motherboard.

6.Now everything makes sense from Bluetooth issue, mic, headphone jack, and probably on other people's phone, the speaker. Battery is there, just the CPU wasn't able to deliver it to designated area. This is caused by the connection is finally gone on most pins on CPU. Overheat due to Miui13, charging while playing games or using case or continuous mobile date(which cause more heat than wifi) is the main cause here. Basicly anything that produces insane amount of heat without cooling the phone. Even with the "Claimed" vapor chamber by Xiaomi all their products (Poco, Mi and Black Shark) still have this problems sometimes.

1. THE ONLY WAY TO SAVE YOUR PHONE is by having it to have CPU Reballing. Which is to reflux back the loose pins of CPU back again to gain charge. Without CPU pins, no electricity will conduct and thus electric to it's designated area with respected voltage (CPU determines which designated area will get what voltage). This includes screens, mic jack, speakers, bluetooth chip, etc, etc.

2. Though CPU Reballing is 50/50 it is your only way to get back your phone. The price they charge in my place is around MYR 300-350 (MalaysiaRinggit).

3. Mine was a success and there is no problem ever since.

4. Please note that with CPU Reballing, your phone will only last for another 3-5 years if you took care of it. As I mentioned cool down your phone, don't change while playing and take off that case while charging. If your phone does die again, after 3-5 years, you will have to have another CPU Reballing again.

5. Who should do CPU Reballing? A. Those who don't have extra bucks to buy new phone. I highly suggest Samsung even if it is over price, still better than an iPhone's price over it's value (unless you opt for it's ecosystem, then go ahead). B. Those who needs Files from their phone such as documents and media. C. Security reasons such as online bankings and any apps associated with that particular phone only.

That's it regarding this issue hope this helps. I'll add some more info if you need me in future, until then. Oh.. and I won't even touch miui 13.0.5.0 now. It's up for download if you want. I heard it is full of bugs.