Greetings to all. Today I tried to fix the time zone by this way and got a broken scope with eternal logo
This happened to me too!
I thought it was a random glitch, but apparently it wasn't, and it is reproducible. I edited the time zone in the boot script, replacing the original value with Europe/Kiev -- and I did verify in the command line that it indeed worked, meaning the TZ name was correct -- and on next reboot there was that eternal logo after a quiet click about halfway of the expected boot process.
It did boot eventually, however. I am not sure what exactly helped. I tried various things: connect or disconnect ethernet and wifi, wait several minutes or hours before the next attempt (maybe until morning, I don't remember), with the USB power cable disconnected. At some point it booted and it was able to connect to network, I don't remember if it was wired or wireless. It took some maybe 10-20 boot attempts in total.
Since changing the timezone to a non-factory one causes boot trouble, it means that the boot sequence is designed terribly wrong. I suspect that there are some decisions as to when various parts should be started that are made based on the text representation of current time -- and if it suddenly changes mid-boot, which is the case when you change the TZ, something is going to see an unexpected (e.g. negative) time difference and fail.
Now, worst case, you can always take the SD card out, back it up, and ideally put aside in a safe place, then get a new SD card (not necessarily 32 GB -- can be 64 GB or more), and write the backup image to it. Then, mount the file system (you need the /rigol partition), which you can do knowing the offset (
man mount, search for "LOOP-DEVICE SUPPORT"; fs offsets were posted several pages earlier in this thread), and revert the changes you made to the boot script.
Once you get it back working again, make a fresh backup of the SD card and save it somewhere safe.