Japanese retailer Enterking has posted a warning on its website which notifies customers that the use of flashcarts on 3DS could result in their systems getting bricked by firmware updates.
According to a post over on GoNintendo, Enterking said this could be the case when using illegal downloaded ROMs.
"Dear customers who resell Nintendo 3DS," reads the site, "in case you use equipment which is illegal or unapproved by Nintendo or if you do customization which is unapproved by Nintendo, there is a possibility that Nintendo 3DS become non-bootable by a system update.
Because of an agreement with Nintendo, Enterking refuses to buy 3DS system with a record of illegal or unapproved equipment having been used on it.
When asked about the possibility of a system becoming virtually useless after a firmware update, Nintendo issued the following response to Eurogamer:
"We do not discuss product security details (for obvious reasons), nor can we discuss the details of countermeasures available in the Nintendo 3DS system. Nintendo 3DS has the most up-to-date technology. The security has been designed to protect both the creative works in the software and to protect the Nintendo 3DS hardware system itself."