Here is how I unlocked 200 MHz bandwidth on my 60 MHz Hantek DSO5062B oscilloscope. If anything is unclear, feel free to ask me questions.
All credits to tinhead on the EEVBlog forums.
Source:
http://www.eevblog.com/forum/chat/hantek-tekway-dso-hack-get-200mhz-bw-for-free/
Firmware backup tool:
http://www.eevblog.com/forum/chat/hantek-tekway-dso-hack-get-200mhz-bw-for-free/msg35683/#msg35683
UART connector pinout:
http://www.eevblog.com/forum/chat/hantek-tekway-dso-hack-get-200mhz-bw-for-free/msg21171/#msg21171