install 3.10 to catalina installer but cannot boot from USB drive

[kingrhy]

I just want update HAC pkg from 2.17 to 3.10, but after I install 3.10 pkg to USB driver successful(already with catalina install), and try to boot from USB DRIVE. its always failed. I can see two opencore menu. first is from USB. secound is OS boot . when I select first. screen will black and not booting .then back to boot menu. anyone who can told me how to boot from USB drive? thanks

[kingrhy]

I misunderstanding about how to boot to USB drive. problem fix already. please ignore this topic

[kingrhy]

hold alt key until booting to boot menu. but I press F10.