XPS 13 7390 - LED Flashing Coin-cell battery failure

Yes. I've tried using a new battery already but same problem. 

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@Den2019 wrote:

I’ve tried to remove the CMOS battery and plugging it in but no success. 

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I don't understand what that means. If you received LED notification of a failed coin-cell battery, then you should replace it with a new one. I can't tell if you removed the old one and reconnected the old one, or if you couldn't remove it (you said "no success"), or what.

Remove the old CMOS battery and replace it with a brand new battery. Here are the steps from the service manual.

Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. I know many people do such work without this, but it's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard.

That means the clock chip itself is bad, and that part cannot be replaced short of replacing the entire system board.

And if the issue is a no-POST, note that neither a clock nor a reserve battery would cause that.  There is more wrong than just the clock battery or chip.