Help! I can't update my BIOS after installing Debian

Hi, everyone.

I've been dealing with this problem for a few days.

I installed Debian 13 in my Dell Inspiron 15 3515 after 4 years of using Win 10/11, the OS my device came with. After that, I've been seeing the infamous blue screen loop "boot option restoration". Pressing any key and selecting "continue boot" or "always continue boot", it goes to GRUB and the sysytem starts normally, but the screen shows up again in the next initialization. If I do nothing, the computer restarts and the screen shows up again.

blue screen written \"boot option restoration. press any key to stop system reset. Reseting in 4 seconds...\"

Blue screen written \"Boot Option Restoration\" and a menu with the options \"Reset system. Continue boot. Always continue boot\"

I've read this forum discussion that someone said that had this problem and it got a firmware flash update to restore. In Fedora forum somone related a similar problem, but the discussion didn't advance.

It bothers me, but it's not a big problem by itself. But I went to Dell's drivers list, there's a new bios update pending from feb 10th. KDE Discover also had notified me from this. I tried to install the update, this blue screen kicks in and no update occurs.

Another info: If I press F12, I can acces the UEFI options. In the BIOS setting, UEFI tab, the list is blank.

Using LVFS "fwupdmgr get-devices" gives me that the update failed because "boot entry missing: no 'Linux Firmware Updater' entry found" which I can't gather any useful info online, but I think it's because my system don't have, or can't find, the files to procced with the update and it can be related with the previous loop problem.

If it's the case that the system can't find the files, in my installation I used assisted LVM to partition my SSD and later had to change it using a live distro (I don't remember if the problem appeared before or after). I also selected the option to install GRUB in a flash drive (If I am not remembering wrong).

I tried to do the fresh restart by the bios (failed), and using "fwupdmgr reinstall" (failed). In my laptop's manual it says it doesn't have a cmos battery. I looked up online but I am confused on how I can clean the NVRAM in this case.

My question is: what should I do first? Reinstall debian (less risky, a lot of work), try a hard reset by disconecting the lithium battery (not sure it works) or try to use a flash driver to update the bios (also, instructions unclear, the best list I found was to use two flash drivers, one for the bios update and one for windows. This are the dell instructions, but I am not sure where to find this file and I don't believe the UEFI can run a .exe).

I am asking here because I am afraid of damaging my laptop in reseting or doing a flash bios update, as it is the only laptop I have to study and I am not in conditions to buy another. Also, I don't want to spend hours reinstalling Debian and all the software I need for it to be in vain.