A couple of years ago, the hatch wasn't closed tightly, and that little light stayed lit for a few days and killed the battery. I bought a new battery and then charged the old one back to usefulness. Today, the battery was completely dead. Not even the door locks would work. I used my little TackLife jumper to get it started, but I had to use it again after a twenty-mile drive.

I have it on the battery charger now, so I'm hoping it will be okay. Unfortunately, the radio is also dead, and it sometimes shows me a keypad to enter a code. Removing one battery and installing another didn't cause the radio to go dead, so why should a dead battery cause it to need the code? That didn't happen the last time the battery died. I wonder how much the dealer is going to charge to give me the code. : (

EDITED: After driving around a bit, the radio decided to work without me entering numbers on the LCD. I pressed the power button in for several seconds, and it came to life. Thanks to Woof (below) for that idea.
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For what it's worth on my 2018:
I had a problem when I upgraded my battery to the larger size. I had the power disconnected from the car for too long and the security system (tied in to the radio) got irritated and gave me this message "Press and hold the power button for 2 seconds to enable the system". Took a lot of searching to find out that the power button is simply the radio volume control knob.

The note I wrote to my future self in case this happens again reads:

"With the car running press the radio volume control for several seconds and that should clear any messages and restore the car's security system. Don't do this with the engine off because then you will be asked to enter a security code which you don't have!"

Don't know if you had volume control knobs from 2015 to 2017.

 

You can get the code for free from Honda Customer Care. I got mine online. It's not a big deal. You will most likely need the VIN and the number displayed on the radio but a google search will verify what you need. VIN for sure.

 

Thanks for the tip. Looking online, it said I would need the VIN and also the S/N of the radio. That was installed under warranty, and I have no idea what it could be. That was done five years ago.