I have a Thinkpad Lenovo X1 Carbon 3rd generation.
Few month ago an official technician replace the screen panel and the motherboard.
Then I gave the X1 to my daughter.
Now the X1 has a problem : the bios date is automatically reset to 01/01/2001 after some hours without using it, it wont start without the AC adaptor.
So I thought it is a CMOS battery issue and I start to open the X1 in order to replace it.
I saw a guy on a youtube video open the X1 2nd generation and I saw the CMOS battery on the rear side of the motherboard.
So I opened my X1, removed all elements in order to access and removed the MB. When I look at his back...no CMOS battery ! There is the location for the battery, there is the connector for the battery but nothing !!!

Do you know where is this CMOS battery ???
Thanks !