HP Prime bricked after update

[XY0797]

Hello, I updated my HP prime a few days ago and installed Firmware 20210505. My HP primes is V1 version, Firmware 20200116. It was damaged during the update, but reference https://www.hpmuseum.org/forum/thread-15862.html , I fixed it.
To my great shock, the third day after it was repaired, it broke down again.
I did some physics calculations that day. I normally turned it off (Shift + ON). After a few minutes, I wanted to turn it on again, but it didn't respond. I tried press Symb+ON, ON+Apps+Esc, Symb+Reset(press the button on the back with a pin and release the pin).
But no change :-(
The screen of the calculator is always black, but when the battery is removed and put in, the screen has a faint flash. I try again after full charge, but it is still invalid.
I'm almost desperate.
But strangely enough, after I replaced the calculator battery with a 4-volt regulated power supply, I measured that the calculator always had 0.34 watts of power.
I don't know if I'm the only one with this problem. Have you ever experienced it?