You were not given any steps different than we give thousands of others here successfully.
There is nothing about formatting a flash stick installer that could exacerbate your computer's random shutdown problem.
Check all cable connections to your mobo and hardware especially the new HD. Try unplugging the DVD drive which Theog suspects is the problem.
Reset the CMOS: Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS
Test your RAM and HD now with bootable CD scans: RAM - Test with Memtest86+ Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp
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