Real life GTA cheat code - Fixing broken firmware on bose soundlink mini II 

So I got myself a Bose Mini SoundLink II speaker a while back. It's a great little speaker with some impressive dynamic range and power in such a small box.

All was good until one day, I let it discharge too much and somehow, the firmware on the device got corrupted. The speaker would no longer charge, instead showing a red flashing light.

I went online, read forum posts and even contacted Bose support. Everyone told me to put it in shipping mode and back... but to no avail.
Bose ended up telling me to ship it to them and they would fix it, but since it was no longer un guarantee, I would pay for shipping and the repair. This would cost way more than just buying the speaker second hand on Ebay, so I opted to not fix it.

Fast forward to multiple months later, and I stumble upon a [youtube video](https://www.youtube.com/watch?v=GSx7GgYrE7Q), with music in the right ear and explanations in the left, telling me there is actually a way of fixing this. All you do, is download the firmware update software from [Bose's website](https://btu.bose.com/) and flash new firmware on it.

I unfortunately already tried this, but since my Bose is already on the latest version, the tool won't even attempt to update it. But this is when I am transmitted the ancient knowledge, a cheat code not even Bose support know's about:

A, D, V, Up, Down

And just like that, the firmware update software is now in dev mode and will allow flashing of old and current firmware (you enter this code on the web-interface of the firmware update tool).

I flash my speaker with the current firmware. It gets stuck at about 80% but this time, it is actually charging. I allow it to charge for a few hours, then flashed it a second time. And this time it works.

I wonder what other cheat codes exists out there... and why Bose creates tools that are never used.