Hello,
Since they're under different product codes, they could have easily been manufactured at different dates. And in between that time the factory bootloader must have changed.
From hardware and software perspectives T03020 and T033C0 are identical in every way. Only difference is what's contained in each package (one has GPS antenna and DIN Rail, the other does not).
So it could be due to the bootloader. I'll see what I can do to get the latest version uploaded to the Wiki. I'll respond back to you later regarding this.
But it's doubtful. I have the same bootloader version and it works fine. My guess is that this could be a hardware problem.
I suggest you fill out this RMA form and wait for a Teltonika sales manager to contact you. They'll give you some questions from Teltonika's technical support in order to determine whether the device is eligible for repair/replacement.
You can read up more on Teltonika's warranty policy here.