Hi,

The problem could also be the Power button itself, not making good contact when it is being pressed down.

Unfortunately, the power button is part of the keyboard assembly and its' wiring is in the flex cable connection between the keyboard assembly and the motherboard.

To prove if the button was the problem would involve removing the keyboard. You could then try to prove continuity through the button when it is pressed by using an Ohmmeter to try and locate the wires, at the flex cable connector point, which are connected to the button. Even if you prove that the button is intermittently faulty as it appears that there are no replacement buttons available the keyboard would have to be replaced.

Here is a link to the service manual for your laptop.

https://download.lenovo.com/ibmdl/pub/pc...

Scroll to the bottom of p.60 onward to view the procedure to remove the keyboard assembly.

Here is a link to the parts list for the laptop. Scroll down to find the section on keyboards.

https://download.lenovo.com/parts/ThinkP...

Keyboards are 'country' orientated, e.g. USA, France, Germany etc. Select the keyboard part number suitable to your particular 'country'. The part number should also be stamped on the underside of the keyboard. The term 'Secondary' next to the keyboard entry means that the keyboard is not 'backlit', Primary means that it is backlit.

As an example here are links to 2 suppliers of a USA keyboard, one secondary the other primary. It is not a recommendation to use one or the other (depending on what you need) it is shown to give an idea of the cost of the part. To find other suppliers that may suit you better, simply search online using the part number only to get results.

USA 04x1201 secondary -not backlit

USA 04x1240 primary - backlit

Hopefully this is of some help.