You're running Windows 7 on your AMD machine, heard about Meltdown/Spectre and did the right thing by updating your OS. And then your PC starts BSODing or worse, fails to boot at all. Fortunately, you don't have to reformat if you can access the recovery console or have your system rescue disc handy.
If KB4056894 is giving you grief, follow the advice of Reddit user "zip369":
On startup, press F8 and select Repair Your Computer. From there, open a command prompt window. Check that the Windows drive is mapped by running
Run the command
dism /image:d:\ /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~7601.24002.1.4 /norestart
It should say processing 1 of 1 and show a progress bar. If all goes well, it will say completed successfully and you can restart into Windows.
On the other hand, KB4056897 can be removed by using the method below, as described by user "WakeXT":
Had the same problem on a system with an AMD X2 4800+ when I installed KB4056897 (security-only update).
Repair disc command prompt with
DISM /image:X:\ /cleanup-image /revertpendingactions(X being the drive letter assigned to your boot drive)
worked for me to get it booting again.
Hopefully, one of these will fix the issue. Worst case scenario, you have to reinstall, but that's probably what you were going to do anyway.
Problems with Windows 7 Quality Rollup (KB4056894) [Reddit, via gHacks]