Problema encontrado: Bootmgr no está instalado.
Problema encontrado: Bootmgr no está instalado.
If you're highly tech-savvy, you can manually craft a boot sector on your boot drive and resolve the issue, though it demands significant typing effort and may cause unexpected complications. A startup repair attempt sometimes succeeds. The safest approach is to wipe the drive and begin anew.
Your updated bios no longer list your boot drive for selection, but it appears to be detected during the startup screen.
It's been some time since I worked with BIOS settings, but I can't locate my boot drive. It's a 4.0 1TB SSD. The system lists the other drives, but not the boot drive. After the BIOS update on the first boot screen, it was detected successfully.
The issue involves the Sabrent Rocket SSD, which uses PCI-E Gen 4 NVMe with 2TB capacity. The boot process isn't changing USB names, so you probably still have recovery media attached. Boot entries #1 and #3 share the same partition sizes and volume names, but #1 is set to UEFI mode, while #3 isn't. You're unsure if the machine has multiple NVMe drives or if a single drive was split into two volumes. It's unclear whether you assembled the system yourself or had it built by a vendor. The Lexar volume's purpose and its placement in an EX16 slot aren't clear to you.
Win10 was once possible on a MBR drive. It might still work, but changing an existing installation from UEFI to CSM isn't likely. The installation probably needs to be completely erased before proceeding.
Only units featuring an UEFI partition can be chosen as the boot source. This confirms the idea that the UEFI partition resided on a hard disk rather than the primary boot device.