We need to see inside. for example:
If your DSO6014A have four of these (https://www.eevblog.com/forum/repair/keysight-mso7034b-teardown-and-repair/msg964822/#msg964822) then no problem, you can tweak it to achieve a BW of 500 MHz and 4GSPS, easily. Ie, you got a DSO6054A.
I did the license upgrade to my 7014A long ago, but there was a comment somewhere (I think from Mike) that the 100MHz units were very different from the higher bandwidth ones and couldn't be upgraded.
But mine does look like the photos of High Voltage's 7034B. It has the QFN input parts and 5 heatsinks.
I've looked through the threads but the only specific instructions I've found were for a DSOX3000 : it consisted of some changes to the input components and some link changes. The input components look similar but links are, I think, different : there are some notes about link settings on the various 5/6/7000 boards but I didn't find a complete list that included the 7000 series.
Can someone point me to the description of the 6014A upgrade please, or to any other postings that help ?