What I tried to say: If the information you're looking for isn't readily available, try to figure it out yourself. I've got a Hantek HDG2002B arbitrary function generator that I modified heavily, made mistakes, bricked it but got it going again better than ever before. I guess the basic system is very similar, a Samsung SoC running Linux with U-Boot loader to start it. There's a UART running a console to hack into the system. So just do some reading, back-up the existing NAND Flash partitions and do some experiments of your own. With the system you've got, you can always return back to the original configuration if something goes wrong. And you may find out which firmware suits your oscilloscope best and many more things.
Maybe you could even provide some useful information for others this way. A forum like this isn't intended to be a one-way street. Other, possibly more experienced users will be much more willing to help you if they see you're not only demanding but also trying to contribute. So far, your postings write a different picture. Maybe you should read them again with a little bit calmed down state of mind. You've got an old, rather basic/low cost oscilloscope that's long time out of warranty. What do you expect from the vendor/manufacturer? No company can support an old product forever if they want to stay in business. Such is life.
But you can learn a lot and it's a lot of fun finding things out yourself, just start it. Anyway, this what all this engineering business, that most of us are involved in, is about. And take it easy if you don't succeed initially and try to use a polite language if you want to get others to help you. Patience is a virtue...
Good luck,
Thomas