Further info, I tried to update the bootloader and got:
Artemis Bootloader Upload
Baud: 115200
File: /Applications/ArtemisUploader.app/Contents/MacOS/resource/artemis_svl.bin
Port: /dev/tty.usbserial-1420
Header Size = 0x80
original app_size 0x328c ( 12940 )
load_address 0xc000 ( 49152 )
app_size 0x328c ( 12940 )
w0 = 0xcb00330c
Security Value 0x10
w2 = 0x10008080
addrWord = 0xc000
versionKeyWord = 0x0
child0/feature = 0xffffffff
child1 = 0xffffffff
crc = 0xc703da31
Writing to file /var/folders/7y/kbd7y0554s3dqwz33x49wvh00000gn/T_OTA_blob.bin
testing: /var/folders/7y/kbd7y0554s3dqwz33x49wvh00000gn/T_OTA_blob.bin
Header Size = 0x60
app_size 0x330c ( 13068 )
Writing to file /var/folders/7y/kbd7y0554s3dqwz33x49wvh00000gn/T_Wired_OTA_blob.bin
Image from 0x0 to 0x330c will be loaded at 0x20000
Connecting over serial port /dev/tty.usbserial-1420…
Baud rate: 115200
Sending Hello.
No response for command 0x00000000
Failed to respond
Fail
Sending Hello.
No response for command 0x00000000
Failed to respond
Fail
Sending Hello.
No response for command 0x00000000
Failed to respond
Fail
Tries = 3
Upload failed
Complete.