All,
Have successfully updated the firmware today now running 7.0.2EU
I use the https://smile.amazon.co.uk/gp/product/B07DLZPV7Q/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 as it performs both functions should I need the TTL side at some point.
The commands I used are all done on a Win10 PC from the command prompt
avrdude -c stk500v2 -P COM14 -p atmega328p -U eeprom:r:oldevse.hex:i
This makes a copy of the eeprom to file oldevse.hex
Then
avrdude -c stk500v2 -P COM14 -p atmega328p -U flash:r:oldevse1.hex:i
This makes a copy of the flash to file oldevse1.hex
Then I flashed the new one in with
avrdude -c stk500v2 -P COM14 -p atmega328p -U flash:w:openevse.hex
After a power cycle and all is good 
Not 100% sure what all the changes were between V5 and V7 but I have them now.
John