X270/X280 won't start after removing back over without AC adapter

[onespeedbiker]

This happened to me with both computers. The first time I was installing a backlit keyboard in my X270 (a lot of disassembly). Afterwards the button light would not come on and it would not start. I thought I had done something wrong or the keyboard was faulty so I reinstalled the old keyboard and the same thing happened. At this point I figured I had broken something, but had the idea of plugging in the AC adapter. This resulted in the button light coming on, but it still didn't boot. At this point I just left it alone and almost 2 minutes later, it booted to set the date and time (I had to disconnect the CMOS battery to install the keyboard), and then it miraculously booted. I then reinstalled the new keyboard and the same sequence occured (it's amazing how undaunting a procedure becomes after you do it three times).

Skip forward a couple weeks and I bought a X280 on eBay and replaced the SATA M2 SSD with a NVME SSD. Very easily accomplished, but again, it would not boot (I cloned the OS to the new SSD prior to the reinstall) without plugging in the AC adapter, however his time it booted much faster because I had not unplugged the CMOS battery.

This is something I had not heard of before and found it odd (I know I did a similar SSD swap in the X270 years ago, but I don't remember this happening, but it might have). I wonder if it was because I turned off the internal battery in the BIOS (UEFI) combined with the back cover switch. Anyone know?

[dr_st]

AFAIR, once you turn off the built-in battery in the BIOS, the laptop will not power on without connecting an AC adapter first. It is by design.

[onespeedbiker]

I did not know that. Thanks