Kernel 4.4 boots fine on my Lenovo ThinkPad T500. Kernel 4.5 gets to the point of the font switch from the large initial font, to the full size screen small fonts and then hangs. I have tried integrated graphics as well as switchable with the same result – at some time in the past kernels would not boot in switchable mode but would in integrated or discrete graphics mode. It seems this is not the case here, it just will not progress at all in any mode. If you let e know what data is needed to help with this problem I can provide.
Kernel 4.5.0-0.rc4.git2.1 appears to boot fine on Lenovo ThinkPad T500, so whatever was the problem appears to have gone away.