Force / replace boot.wim image, SCCM 2012

If you want to use specific boot image then:
1) Assign your new boot image to [Boot Images] section. Do not distribute it!

2) Open image [Properties]

3) Make sure to check "Deploy this boot image from the PXE-enabled distribution point":

4) Distribute content:

5) Wait for success status

6) Create new task sequence

7) make sure you assign just exact same boot image you created before:

8) Complete task sequence

9) Deploy task sequence

10) Celebrate. Boot image now is replaced.