Following the instructions in "The RadioToday Guide to the IC-705", I have successfully upgraded the firmware from V1.12 to V1.24. All appears to have gone correctly. The next thing is to get a suitable interface cable from the rig to the PC and try FT8 and rig control. Some have used cables with ferrite toroids on or isolators to minimise ground loops.
As you can tell, I am taking things very slowly. With my "brain fog" (probably as a result of my 2013 stroke) it is all too easy to make mistakes. Jobs that would once have seemed trivial are now quite hard. Even just unpacking the microSD card from the packaging was a challenge!
UPDATE 2029z: Since doing the firmware update, a couple of new icons have appeared. The SD card is there, but flashing (why?) and there is an adjacent red circle. I am sure I shall find out what these are soon! I was able to have a 2m FM net OK this evening, but avoided touching anything just in case it all went wrong! Investigation needed, HI.