I don’t quite understand: I assume that the USB is first in the BootOrder since you were able to boot from the key to install UB? Unless it’s because Linpus Lite takes over automatically.
What is the make and model of your computer?
Are the BIOS access keys not displayed at startup?
Launch the terminal (Ctrl Alt t) and send the return from efibootmgr.
On my macbook 2012 I just have to hold down the command key when its starting and then a mac window appears asking what you want to boot with - select the USB drive at that point.
me@Mac:~$ efibootmgr
BootCurrent: 0000
Timeout: 5 seconds
BootOrder: 0000,0080
Boot0000* Ubuntu HD(1,GPT,f835660a-cc58-438c-ab01-364e47dbb937,0x800,0x219800)/File(\EFI\ubuntu\shimx64.efi)
Boot0080* Mac OS X PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\5D89A584-CE84-3EB4-A9AC-36FB9AB82201\System\Library\CoreServices\boot.efi)
Boot0081* Mac OS X PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\366CF3F3-BED2-41B9-9432-BC5AE752DBAC\System\Library\CoreServices\boot.efi)
Boot0082* PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\366CF3F3-BED2-41B9-9432-BC5AE752DBAC\System\Library\CoreServices\boot.efi)
BootFFFF* PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(3,GPT,26771025-0c57-4592-a96c-ebc117ec80ee,0x58ea9b,0x8000)/File(\System\Library\CoreServices\boot.efi)
This is from efibootmgr me@Mac:~$ efibootmgr
BootCurrent: 0000
Timeout: 5 seconds
BootOrder: 0000,0080
Boot0000* Ubuntu HD(1,GPT,f835660a-cc58-438c-ab01-364e47dbb937,0x800,0x219800)/File(\EFI\ubuntu\shimx64.efi)
Boot0080* Mac OS X PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\5D89A584-CE84-3EB4-A9AC-36FB9AB82201\System\Library\CoreServices\boot.efi)
Boot0081* Mac OS X PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\366CF3F3-BED2-41B9-9432-BC5AE752DBAC\System\Library\CoreServices\boot.efi)
Boot0082* PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(2,GPT,71a76937-fb25-47f3-a785-76398e7eab3d,0x12c06,0x583e95)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,ce6e64598d7c854ab55d628117d77d69)/File(\366CF3F3-BED2-41B9-9432-BC5AE752DBAC\System\Library\CoreServices\boot.efi)
BootFFFF* PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)//HD(3,GPT,26771025-0c57-4592-a96c-ebc117ec80ee,0x58ea9b,0x8000)/File(\System\Library\CoreServices\boot.efi)