I have read all the related threads (over the last 3 days of my attempts) but haven't come across this problem that I discovered by trial and error.
1. So LE 10.0 latest (and another related distro 10.1.1 and 10.0.9) just doesn't boot on my Dell E74560 laptop with the latest A24 (Jun'20) BIOS, in default Legacy Boot. A19 (Feb'18) had exactly the same behavior.
The laptop always boots in Windows 10 on HDD as usual.
On an older Dell PC, it just hangs at the Dell splash showing F2/F12 Settings/Boot menu.
2. This is USB boot, not the HDD install which stage I never got to, trying with LE USB Creator, Rufus and Win32DiskImager. All the files that should be there show up properly in Windows File manager, and I was able to get into syslinux.cfg to edit "installer" to "run" etc.
I tried various USB2.0 sticks with all the 3 USB3.0 laptop slots. No luck.
Deleting the EFI /BOOT folder or its files for Legacy Boot made no difference.
3. Interestingly another USB2.0 stick with Ubuntu Mate 20.04 via Universal USB Installer booted fine on the same laptop under Legacy Boot.
4. However, when I switched to UEFI boot on my Dell E7450, LE 10.0 (and the other distro) booted right away, with the 5 sec menu for install, run or live selection appearing.
It shows UEFI ROM Build 42:32:36.
5. The problem: Unluckily the Dell E7450 in UEFI mode doesn't detect the hard drive, so no go !
I tried all kinds of online fixes, no luck. E.g.,
This seems a common issue from googling, and Dell advises that one needs to reinstall Windows 10 after switching from Legacy Boot to UEFI first (looks like the OS was installed with Legacy Boot, hence this issue):
I want to avoid the reinstall pain for the additional potential of getting into some other issues !
Is there a way to configure the boot path in syslinux.cfg for Legacy Boot, which is the recommended BIOS anyway?
Curiously while I always changed the default GPT to MBR under Rufus, I noticed that the USB label under UEFI was something like " Pci.Root..USB...HD(1, GPT...)"
Any insights ?