HP 255 G5 BIOS Rollback

[Necoarc]

Hey, people!

Can you help me, please?

I can't rollback to previous version of BIOS after update to the latest.
It seems that HP locked rollback ability, though f.33 isn't critical update version.

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HP 255 G5 https://support.hp.com/gb-en/drivers/sel...c/10193058
Insyde BIOS
BIOS file name - 082F6.bin
BIOS Current - F.33 
BIOS Previous - F.24
BIOS versions tried - f22, f24, f30 and f32
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Tried rollback through Win+B, with USB flash and F2->System Diagnostics->Firmware Management w/o success.
It says "Unable to read signature file."
Also used PhoenixTool 2.6.6., but it didn't show BIOS Recovery filenames. I even created SLIC BIOS file (ofc, he never worked for rollback due to validation error).

Please, help me someone!

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p.s. Fan control is messed up after update to the latest BIOS on HP 255 G5 laptop.
Now it spins on high speed all the time, right after pushing Power On button, and so on. 
Fan noise is driving me crazy for few days already. But there is no overheating.