If no serial, it may have JTAG (for initial factory programming). A bit more difficult, but there are plenty of DIY solutions for that too, some of which may be adaptable to kindles:
HairyDairyMaid JTAG Debrick Utility
When somebody bricks one of these new kindles, it may be worth trying the JTAG debricking methods.
Another MUCH LESS SAFE approach would be the "pin shorting" method, to make the device think it has corrupt flash, so it reverts to device firmware update (DFU or TFTP) mode:
Bricked Linksys WRT54G repair instructions
Something similar may work on some kindle devices for which there is no other approach, and you cannot return it to amazon for a replacement (though only as a last resort due to risk of hardware damage). I debricked plenty of routers that way (before safer methods were developed), though a kindle Oasis is a bit expensive to take pin-shorting casually -- JTAG is worth the extra effort if this kindle model supports it (though TTL serial and USB are the simplest basic debricking interfaces, if we can find out how and where).
