I would look closely at your install to be sure that you did not remove or loosen any cables. IBM thinkpads (as well as many other types of laptops) usually use a thin multi-wired 'cable' that is loosly secured by a small plastic clip. If they become loose, hardware could fail. Take it apart again and check for this.

Usually, when you powerup and do not get anything, it could be either a power supply or BIOS. Both of those would cost you a lot of money with a Thinkpad computer. However, if it comes to this, people will auction parts for thinkpads on e-bay for a decent price. You may be able to swap a motherboard or power supply if you have problems. Thinkpads are so expensive these days that it would probably cost you too much to go to IBM.

I am sorry this happened to you. It is a rare occurance but usually means the demise of a computer. Is it possible that you wired the hard drive incorrectly? This will also cause the computer to not boot. Especially if the power to the Hard Drive is connected incorrectly.

I would check all your connections. My suspect would be the power plug into the hard drive. If you are unsuccessful, then take to your local shop to have them take a look at it. They will probably take a look at if for free and give you an estimate of what is wrong.