For most kernel panics, updating your software is all you have to do.
To fix it enter a text-only console and either replace 4.8.0-44-generic with the more stable default kernel version or run Remember that 16.04.2 (they weren't specific what version they installed, but it looks like .2) comes with kernel 4.8, not 4.4.
When the system boots up, press "F2” to enter UEFI setup screen. Go to Control Panel Sound and select "HDMI output”. We have tested some memory modules on AM4 platform and users can refer to our suggested module list for choosing the finest ones to pair with your AM4 motherboard. Please load the BIOS default settings and then save the settings. Enter into BIOS setup and choose "Instant Flash" to upgrade to the latest BIOS Step 5.
Answer: Requirements: O/S: Windows 10 Receiver / decoder: Onkyo TX-NR 747 or other receiver supports HDCP 2.2 Playback Software: Power DVD 14 (from Pioneer Ultra HD Blu-ray Drive) Configuration: M/B: Z270 Gaming-ITX/ac BIOS: P1.20 Setup: 1. Download the driver from the following link: Z270 Gaming-ITXac/asp#os W1064 3. Please run "Ultra Blu-ray advisor” to see if all "Pass”. Put a 4K movie BD disc into the Pioneer Ultra HD Blu-ray drive. Please keep tracking the latest BIOS update on ASRock official website.
It might be better to first try and boot the previous kernel from the GRUB menu and see if that works.
Then I'd reinstall/update to 16.04.whatever they were trying to update to.