Fio V3 - can't load sketch on recent purchased Fio

Development Boards Arduino
1

I recently bought 2 Fi0 V3 (DEV-11520, March 11th). I have used this arduino variant in the past.

Sadly I can not load my sketch onto either of the new devices. I can, however, load the software on to a Fio V3 that I purchased in late January. They are all the same version and I can see no discernible difference. They are all red PCBs, they are labeled Fio V3, and all have 11-1-11 on the back.

When I load to the older one, I can see the TX/RX lights blink and the charge light seems to pulse; code runs. On the new ones, I see no change at all.

Is there a possibility that these new ones do not have the boot loader software?

Thanks in advance for any tips,

Chris.

2

Any tips on how to determine which bootloader is installed? Or if a bootloader is working properly?

Thanks,

Chris.