I have an Intel NUC5i5RYH (rebadged as a System76 Meerkat), which was delivered with BIOS v.0249, and booted from its M.2 SSD  into Ubuntu 15.04 in around 15 seconds. I was also able to access Intel Visual BIOS settings (on a Dell monitor via miniHDMI-HDMI cable) by pressing F2 at the BIOS logo boot screen.
However, it has also exhibited the well-known 'Ubuntu Suspend > Dead NUC' problem, about which many threads exist here at communities.intel.com – and I've tried updating the BIOS to the (then latest) v.0350, but to no avail: Ubuntu Suspend still bricked my NUC with BIOS v.0350 installed. Only by disassembling the computer, disconnecting/reconnecting the CMOS battery, and reassembling the computer, was I able to get it to start up again.
Now the computer takes two minutes to boot up, and I can no longer access Intel Visual BIOS settings by pressing F2 at either the BIOS logo boot screen or at the Power Button Menu: I just see a blank black screen on both a Dell monitor (miniHDMI-HDMI cable) and a Panasonic HDTV (miniDP-HDMI cable).
I've tried downgrading to the original BIOS v.0249, and upgrading to BIOS v.0352, but to no avail: boot time is still two minutes, and I still cannot access Intel Visual BIOS settings by pressing F2 at either the BIOS logo boot screen or at the Power Button Menu. This is important, because a potential solution to the 'Ubuntu Suspend > Dead NUC' problem, posted by mikec_intel in...
● 'NUC5i7RYH did not wake from sleep mode'
So I'd be very grateful for any assistance in solving these two Intel NUC problems:
(1) Restoring access to Intel Visual BIOS settings, via pressing F2 at either the BIOS logo boot screen or at the Power Button Menu(2) Eliminating the risk of bricking my NUC with each use of Ubuntu Suspend
And if it could be restored to booting into Ubuntu in around 15 seconds, that would be champion.
Thanks in advance for your attention and help.
 Its M.2 SSD: "M.2 SATA: Samsung SSD 850 EVO M.2 250GB : PART 0 : Boot Drive"
PS: I've sought help from System76 tech support, but sad to say they're about as useful as a chocolate teapot – so I'm hoping the Intel NUC community might be of some actual help in addressing these problems.