Thank you very much for your response
The battery you changed before
Any other solutions?

Thank you very much for your response
The charging cable I changed, the battery changed it, and it's still the same
And the problem came up after I changed them because the old battery quickly consumed power
But I will only update the BIOS once and I hope the electricity will not be cut off
Is there no other solution?

Replace the battery

See above.  Does the system sense the AC adapter, or is it "unknown" or "not installed"?

First check:  Does the system recognize the AC adapter, or does it show unknown (F2 at powerup to check).

If unknown, 

1.  Try a new OEM Dell adapter first.   If that doesn't solve the problem,

2.  Replace the DC jack in the system.

If that doesn't solve the problem, the charge circuit is bad - replace the system board.

If the adapter is recognized, but the battery won't charge - replace the battery.

You cannot safely flash the BIOS without a charged, recognized battery.

Thank you for your interest
Yes, the electrical transformer works well and there is no problem

That isn't the point.  The adapter can perfectly run the system and yet show up as unknown -- and if it's not identified by the system, the battery will not charge.

You have a number of possibilities to eliminate systematically:

Make sure the adapter is recognized.  If it is not, the battery won't charge.  If that's the case, try another OEM Dell adapter. 

If that does not solve the problem, replace the DC power jack:

https://www.parts-people.com/index.php?action=item&id=9754

If that does not solve the problem, the charge circuit is fried and the mainboard will need to be replaced.

If the AC adapter is OEM and the system  does recognize it, the battery is either faulty or it's a third party battery the system doesn't recognize (again, check setup;  if the system doesn't recognize the battery, it will not charge.