This of course meant breaking out a screwdriver and removing both covers to examine the board, particularly around the power input area, I spotted a diode that I thought may have protected the radio but this did not explain the fact it was not powering up, so the fuse was examined after I did some digging on the Internet and low and behold it was blown, this was a very lucky escape as I somehow managed to reverse the polarity of the cables as I saw red on one which I thought to be positive, turned out what I saw was actually where the red attached to the black and thus resulted in the situation I found myself in on Wednesday
The radio was then powered with the fuse replaced as noted above (a lower rated fuse is safer than a higher rated fuse because a higher rated fuse is less likely to blow under fault conditions, a lower rated fuse does become a pain because it would be prone to blowing when you don't need it do), the display lit up fine, the memory channels were intact, nothing out of the ordinary, the radio covers were refitted and the speaker reconnected (the Grant II is like the TTI TCB-550 in having a speaker that is plugged onto the board rather than the wires soldered directly, wise choice by both President and Uniden), then the transmitter tests, first of was transmitter power, all within 3 to 4 watts into my salt water dummy load, 12 watts for SSB into the same load, audio was tested on AM and FM only with the receiver being my Midland Alan 42 Multi handheld, all good, receive audio was also tested, not a problem, this radio has had an extremely lucky escape, this has further spurred me on to invest in Anderson Powerpole connectors because those would prevent mishaps like this as they cannot be reversed and also the Fuser 6 unit from SOTABeams to add that extra layer of protection.
I am relieved and hope to get the Grant II on air again as soon as possible.
Also here are the pictures of the Grant II during the testing as well as the fuse how I found it, these are also available to view on my Twitter account.
Remember, red to red, black to black or it will be blew to bits or in my case a blown fuse, well done to President and Uniden for including the diode in this radio, if that was not there I'd have a very expensive paperweight.