Ubuntu-MATE can't boot and no grub menu
 

Novice Linux user and admit I am losing the faith:(
Spent the ENTIRE last weekend trying to get Centos 7 up and running but gave up after numerous Nvidia driver related issues
So I've switched to Ubuntu MATE. For a day or 2 everything was fine.
Then on booting this morning had corrupt display issues.
Then this evening when attempting to boot I couldn't boot at all and instead booted into my 2nd SSD which has Windows 10 installed.

I attempted a bootrepair but was unsuccessful.
Forwarded the pastebin2 url to boot.repair at gmail

One error I was getting while attempting boot repair was the following

I have the following partitions on a 1TB SSD
/boot 200mb
/swap 8GB
/ 20GB
/home (remainder of SSD less 70GB unallocated)

Is it possible my boot partition is still way too small?

Also, as a last resort I tried reinstalling Ubuntu MATE on top of my existing partitions without formatting so as not to lose any data(my application installs)
One error I did encounter was my root partition seemed to have lost its 'root' flag, so I reassigned it.

I'm seriously about to give up and just stick with Windows.
Would appreciate some advice though on possible next troubleshooting steps.

I'm on a dual boot PC but Windows and Ubuntu each have their separate SSDs. However I am wondering if there is something in my BIOS that is causing problems.

I can't afford to lose another weekend reformatting my disk and installing everything from scratch again!
Any feedback appreciated

Grub doesn't work out of the box with GPT partitioning. Windows 10 uses GPT. Getting grub to boot is pretty tricky on such a system. There's a program called: that speaks both GPT and MSDOS partitioning. You can use it to fix the partition table so grub will boot.

The other thing is that the error is telling you to make a > 1MB partition, marked as a bios_grub flag. You could try doing that. Use GParted from a live CD.

Your /boot part. holds the kernel and system maps, initrd, and a few other things like grub. So, 200MB should work.

Most systems have a BIOS boot manager you can access early in the boot process, before grub appears. There might be a message "press some_key for boot menu".You can choose legacy or bios, and that might work to bring up grub.

Since your computer came with Windows 10, I suspect you don't actually have a BIOS in there. You have a UEFI, which is capable of emulating a BIOS but normally works differently.

As far as I know, Ubuntu boots and installs in UEFI mode if it detects one of these chips running in its native mode. This means that it puts GRUB into the efi system partition. This is the way you should always install if you are dual-booting with Windows because it's the only way Windows will boot.

If you installed Ubuntu with your chip in legacy mode (i.e. emulating a BIOS), then the first stage of GRUB would go into the mbr and the second stage would expect to find a small unformatted grub-bios partition to go into (that's the partition it says it can't find).

My guess is that you installed in one mode and are now trying to boot in the other.

What was the boot repair program that you used? Was it a Windows program? That's probably what has screwed things up.