Zotac ZBOX Nano AQ2-BE

I am trying to run FreeBSD 10.3-RELEASE-p7 on Zbox Nano AQ2-BE.
I like how FreeBSD sticks to simple things and just works.

Generally this is
Machine class: amd64
CPU Model: AMD A8-5545M APU with Radeon(tm) HD Graphics
No. of Cores: 4
Graphic card information:
vendor='Advanced Micro Devices, Inc. [AMD/ATI]'
device='Richland [Radeon HD 8510G]'

It is running mainly Linux ATM. The only thing worth to mention is that it run very hot by default with FreeBSD. I had to enable C2 state to avoid fans spinning laud. This brought temperature from 63C to 48C in idle. This is acceptable while Linux is able to go down to 43C in idle.

I am using hibernation even on this "desktop" box as it saves a lot of time to open up all the work after power on, however here FreeBSD fails. It suspends to S3 and even S4 but won't resume (BIOS declares to support both).

I tried stepping thru this howto
and noticed that if beep is enabled, then after resume the long beep occures (monitor is black) and then stops, system shortly beeps like after a normal boot and boots up into Grub. Booting FreeBSD loader from it results in normal startup (no resume).

My question is how the resume should look like. Did I understand correctly that BIOS is responsible for resume and it should resume directly into FreeBSD? There is probably some (FreeBSD?) code run from BIOS that does the beep, but I did not found any details. How could one debug this?

Or is it just "BIOS is broken, you can do nothing about it"?