Is there a reset procedure for the HP Smart 515 that might resolve the E3 error?

While there isn't a traditional 'reset' button, you can perform a factory reset through the printer's control panel (if equipped) or through the HP Smart app. *However*, a factory reset will erase all network settings and preferences, so use this as a last resort. Consult the HP Smart 515 user manual for specific instructions on performing a factory reset.