CMOS battery replacement XPS 13 Plus 9320

@ejn63​ Thank you for the quick response.

The main battery works fine, but if I leave the computer turned off and unplugged for a couple of days, when I turn it back on it enters manufacturer mode because it loses the service tag. I don't know how to avoid it and that's why I thought it might be a CMOS issue.

Has this happened to anyone else? 

The service tag is not stored in battery backed memory - it is stored in an EEPROM.  If the system spontaneously changes to manufacturing mode, the mainboard needs replacement.

@ejn63​ Unfortunately the PC is no longer under warranty and replacing the motherboard is a very expensive procedure.
I’d like to take advantage of your expertise and ask if you have any suggestions for valid alternatives to consider.

The manufacturing mode doesn’t seem to block any particular PC functionalities. It’s just very annoying because it makes the fans run at full speed. If for example there were a way to disable it from the BIOS, that would be great.

You can try having the board repaired (i.e., having the EEPROM chip replaced).  It won't be inexpensive (figure on at least a couple hundred dollars) but may be cheaper than a board replacement.

You will need a true repair shop that can do board level repairs -- not just a generalist shop that simply replaces parts.

Note that despite the quotation of AI chat, there is no CMOS battery in this model.

@ejn63  Do you know if the motherboard replacement due to EEPROM problem is compliant as Prosupport service repair?

If the system is under warranty, yes it should be.

I have a XPS-13 Plus 9320 here that appears to have a similar issue as the OP. It has the nice OLED screen, so I guess it's worth some effort.

It was in storage for 1.5 years (we have other laptops and devices). The main Li-Ion run-battery accidentally drained down to 1%. It charged back-up to 100% and BIOS says Battery Health is Excellent. However, now it is sometimes complaining about the Date-Time not being set properly on boot.

I think there might be a small rechargeable battery (or Super-Capacitor) soldered-onto the motherboard (like the memory is). It reminds me of an iPad inside (but with fans).

I'm hoping that when the bad-thing happened, there is now just some HIDDEN CORRUPTION saved somewhere. To fix it ... instead of just re-setting the Date-Time ... I just tried Resetting to BIOS-Defaults first (to re-initialize and clean).  We'll see if that helps. You at least need to know your laptop's proper settings for AHCI/RAID and SecureBoot. This is on BIOS v2.0.0 for now.