Fails to boot after changing thermal paste.

I've followed closely the instructions given at this website. After putting all the parts back, the macbook boots but stuck at the loading page, the loading bar stop midway and doesn't go any further. I've done all the relevant reset and still to no avail. Did a SMART test, came out verified.

Tried to boot into my USB installer, it stuck at the disk utility loading disk page.

Is this the end of my laptop?