My electric chainsaw. Been conifer pruning today and decided I needed the big guns. Having not used it for years it took me quite a while to find it buried under general detritus in the garage but eventually did, toped up the oil, connected it all up and then... Nothing! Checked the extension cable, RCD, fuse etc. and couldn't work it out. My voltage detector showed there was power but I couldn't get it to work. I was pulling what little hair I have out when I suddenly noticed the front hand guard/chain brake...
Suffice to say there was nothing wrong except that the chain brake was set as operational hence no power to the cutting chain...
Anyway I should have used it earlier because it cuts through conifer trunks and branches (6"-8" thick) like a hot knife through butter. I'm off out there again now to finish off.