Look, I am obviously a big fan of shortcuts, but there if there is one thing we as a society need to give up on, it is the expedited ripening of the avocado. This isn't just like, my opinion, man; Cook's Illustrated feels the same way.
Hard, unripened avocados are quite annoying, and it's natural to want to get them to an edible place as quickly as possible, but time is your best tool here. You may have noticed a few "hacks" on how to do this floating around, the most popular being popping it in the oven for a bit. To see if you could heat your way to toast-worthy avocados, Cook's Illustrated tested out the tip by placing a few of the unripe fruits in a 200-degree oven.
The result? A slightly softer, but slimy avocado. Though heating does help stimulate the production of ethylene gas -- which, according to C.I., "triggers enzymes in the fruit to convert starches to sugars and soften cell walls" -- you'll end up cooking the fruit before it ripens:
While heat does stimulate the production of ethylene gas, there is a limit to both the rate of its production and the ripening reactions it produces -- you can speed the process up only so much. Placing an avocado in a 200-degree oven doesn't actually produce more ethylene or ripen the fruit -- it merely cooks it, which is why our avocado turned slimy rather than softened like a truly ripened fruit.
So skip the oven, and let those things ripen on the counter, or maybe chuck them in a paper bag with a banana (which releases a lot of ehtylene). It will take a few days, but at least your avocado will be soft and spreadable, instead of warm and slimy.
Oven-Ripened Avocados? [Cook's Illustrated]