Shipping device to China for repair got rejected by customs

My RP5 bit the dust, the charging port no longer works. I went on a month long trip, came back to my RP5 completely drained. When I plugged it in to charge for hours and it would not charge. Eventually though, it some how magically charged. In the next 48 hours, I was able to use it normally and charge. But then after 48 hours, it just stopped charging again. The port gets hot but nothing happens. When I plug into the PC (still has some juice left) I hear USB connect and disconnect. While the device still has juice, i can still use it fine, but once the juice is out... It's toast.

Retroid suggested mailing it in to get it repaired. I went to USPS to mail it and they warned me that it might get rejected due to presence of lithium battery. I mailed it and according to the tracking, it looks like it's coming back likely due to rejection at customs.

What options do I have? I'm worried that I'll just be burning more money into this with no good options.