|Just so you know disk cleanup has nothing to do with memory [ram]. It has to do with cleaning up temp/deleted files/install files from your hard drive which frees up space on your hard drive.|
Disk cleanup also did not have anything to do with your booting issue. That is just coincidence. Disk cleanup has no ability to affect the boot files or process.
A more likely culprit is hardware failure or virus infection.
To test if this is a hardware vs software issue the first test is to enter the bios and see if you experience the same system shutdown. If so its a hardware issue requiring skilled repair.
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