Downgrade BIOS on Envy 16 or Force Correct CPU TDP Settings

[Mike975]

I have an HP ENVY 16 with a 13900H.  My CPU is running extremely slow and is TDP limited for some reason. Thermals are fine and far from the throttle limit.  The TDPs are set to  20 W and 45 W after a fresh reinstall of Windows and an update of all the drivers; I have installed Windows three times now, one restore from HP's restore on the hard drive, one restore from the cloud, and one fresh install from a USB drive.  My CPU benchmarks are consistently half of what they should be and what others have reported for this laptop. The laptop is also noticeably slow.  I ran the Time Spy benchmark, and my CPU score is 5700.  If I force the TDP to the stock settings of 45 W turbo boost and 115 W short time turbo boost using Intel's official XTU software that lists this as the stock settings for this CPU, the laptop runs perfectly fine, the score increases to 11475, a 100% speed improvement just but using the correct TDP settings for this CPU.  Others have reported this phenomenon for this model laptop, and others have not; there are threads about this laptop with users sharing performance as it was recently on sale at Best Buy.  I set power settings to performance in Windows; I have tried settings power settings to performance in HP Control Center, but the HP Control Center doesn't seem to work on this laptop.

HP has posted the original BIOS file for this laptop. When I go to install it, the option to flash this BIOS is greyed out.  I am running this laptop's latest version of the BIOS, and I want to rule out the BIOS as the issue. Others have reported for other HP laptops that the latest bios version lowered the TDP of their CPU and killed their performance. 

Is there any way to use software to flash the BIOS with the older one I downloaded from HP? I'm about at my wit's end on this laptop and will sell it at a loss if I can't figure out what is wrong. It is only a month old, and I've barely used it because of these issues.