Done, I tried to flash it with Raspberry Pi 3B and OpenOCD
I was able to recover the boards following the Adafruit Raspberry Pi openocd tutorial here, and some modification into raspberrypi2-native.cfg :
…
bcm2835gpio_swd_nums 25 24
bcm2835gpio_srst_num 18
reset_config srst_only srst_push_pull
…
For wiring from backside odyssey samd21 pin out :
Pi -GPIO Samd21
GND ---------------> GND ( I used top side gpio )
3V ------------------> 3V
24 -----------------> SWDIO
25 -----------------> SWCLK
the odyssey status is off when I flash it 
For bootloader file for smad21 download from here, thank to @CamRodandChief
