W540 boot up problem

[LarryD68]

I have a used W540 Thinkpad running Windows 10 Pro. After a few months of non use with power cord unplugged, I attempt to power up.laptop.

It went through BIOS screen but stopped. Keyboard backlighting, Fn button and F1 and F4 buttons blinks. Power button, dot on i in ThinkPad logo on laptop cover both blink three times, pause and blink three times in pattern. The fans whoosh in time with keyboard blinking but do not spin.

I have tried following solutions to no avail: removed battery and unplugged power cord and pressed powered button 10 times. I removed second HDD and powered up laptop.

Please help.