Of course it is, and if you don't know it, don't think anyone knows. It's time to learn. But... It seems (at least to me) that not knowing is not a shame today, it seems to be a matter of honor.
Most BIOS machines have an option to boot external drives (if bootable) during power-on by pressing F12 or maybe ESC to let you select what drive you want to boot. Also note that the boot partition on the external drive needs to be flagged active. You can check/set the flag with BOOTICE. No need to mess with the BIOS.
No blame no guilt at anyone ........ just an opinion about site matters. This thread is like the truth in slices with a veil on ........ and so are lots of other threads asking for help . If we want to help people we need to have a standard procedure . Something like this ........ but better ---- > https://forums.mydigitallife.net/threads/how-to-feedback-errors-problems.67621/ If we had had full information at the start of this thread it would have been easyer to present some ideas .
Some people more focused on smart answers rather than helping OP. Yes, F12 is a common, but not universal, key that will get into the bios boot device selection. On my ASUS, it is actually F8. And yes, the external device has to have a partition that is marked active. But the OP here has reported a similar boot loop problem when inserting a usb drive or windows dvd. If he was really booting from a different device, he would not see same behavior. Banging F2 key on boot will bring the ASUS into bios setup mode, and a proper submenu can then be found to select only the boot device. Nobody here suggested tampering with other settings.
This was simply an answer to If it's not helpful to the OP and only a smart answer as you call it, I can remove it . Would you prefer that?
@adric: There was nothing with your suggestion. You can use the hot key that directly brings up the bios boot device list, but you can usually also get there from the main bios setup screen. It was the tone of a different post that was not needed.
Was able to boot from Hiren's and it turns out there's too many bad sectors on the disc to fix. I'm able to copy some of the files over, so can save a lot of the data at least. Drive is shot.
Are you able to get it to boot into safe mode at all by launching advanced options from startup repair off the install disk? Similar thing happened to my mom when she had a windows update pending and her battery is completely dead so when she accidentally knocks her power connector out the laptop loses power and something got corrupted, i had to boot safe mode and uninstall the update and reboot a few times through safe mode.
I have had similar problems in the past, more than once, with different computers. The last one I worked on, a couple of months ago, the problem was (apparently) with the UEFI information. And there don't seem to be any good tools for dealing with that. The only reliable way that I have found to re-write / fix the UEFI information is to wipe the hard drive and do a clean install. What I finally did with this last one was to replace the hard drive with a new SSD, perform a clean install of Windows 10, and then mount the old hard drive externally. From there, I was able to use Easeus PCTrans to copy back not only the data but most of the applications. I tried Laplink PCMover first, and it did not work very well. PCTrans was pretty slick, at least in this particular instance.