Sally Hyder, 48, from Edinburgh, made it halfway up – just over 2,000 feet – when she was forced to turn back due to the power failure.
Video by Clare Carswell and Andrew Elliott
And, although she managed to raise half of her £10,000 goal for chosen charity Canine Partners, Ms Hyder is determined to finish the challenge.
Canine Partners provides assistance dogs to disabled people, and 18 months ago Ms Hyder was given Harmony, who she says has changed her life.
She said her biggest wish would be to raise enough money to pay the charity back for Harmony – who cost £10,000 to train.
She said: “There is a huge waiting list for assistance dogs and I hope I can raise enough in my lifetime to allow someone else to have one.
“The effect Harmony has had on my life is indescribable, I no longer have to get people to pick things up for me and I can go out and meet people and lead my life as I knew it before the MS.
“I was devastated on the day to have not reached the top but now I just feel rather wistful and completely determined to get to the top next time.
“I’m treating that one as a trial run, when I do it again in 2012 that will be the big one.
“We know what the problem was now, so next time I can plan for that.”
The team of three guides and Harmony the dog took 10 batteries with them – each weighing six and a half kilograms – which should have been enough to power the wheelchair for 140 miles.
But a problem with the circuit board meant the life of each battery was running down after virtually 10 minutes.
In her gruelling attempt to raise cash, she managed to break a record for being the highest climbing electric wheelchair user.
She said: “My goal initially was to get to the top, then it became about going as far as I could, and to have beaten a record makes me very happy.
“It was very challenging, there were several bogs that I got stuck in along the way and the terrain was very rough and bumpy.
“There was never a moment I considered stopping until I realised we had to.”
Ms Hyder was diagnosed with multiple sclerosis in 1989, aged just 27, but before then she was a keen hillwalker and had climbed a number of Munros.
In fact, in 1988 her now husband Andrew – who accompanied on her quest to conquer Nevis – proposed to her at the base of Mount Everest during a climbing holiday in Nepal.
She said: “Andrew and my 18-year-old son Peter came with me and I could not have done it without their support.
“And the team I had with me were just amazing, every single member of staff from Canine came that day, and the momentum it brought me was enormous.”
Mrs Hyder has a number of fundraisers in the pipeline, including plans to sail down the Caledonian Canal next summer and abseiling on the Forth Road Bridge – which is proving more difficult to arrange because of her condition.
She is also writing a book, to be named Finding Harmony, which is due to be published by Harper Collins in February 2011.
It will tell the story of her life, including a final chapter currently being written about her Ben Nevis escapade.