Trying to get 2015 MacBookPro with hosed hard drive diagnosed / going again

My trusty 2105 15" MacBookPro fritzed out when it hit zero battery while YouTube was streaming. The next morning I got a blinking folder at startup. I sent the harddrive for recovery but it was unrecoverable. There is now an Aura N SSD inside, having serious trouble getting the computer going.

Internet Recovery goes through a countdown / progress bar and then kicks the computer into a restart. Trying to boot from an installable Sierra boot USB gets partway through the Apple progress bar and then kicks the computer into a restart. Running Diagnostics gives a PPT001 error. In single-user mode, I don't know what is relevant, but it does say "SmartBattery: abort polling".

However, there don't seem to be similar issues when I boot from a separate macbook using target disk mode. I can see the Aura N drive, battery, etc.

Are there any next steps other than logic board replacement?