Dash/running Lights/radio Dead

Just put the Miata back on the road after a cold snowy winter here in the North East. Everything fine - then all of a sudden, first time driving after sundown - no interior lights! Found out next day, no running lights as well! Today, radio (after market Alpine head unit) cuts out, restarts, few minutes later cuts out again, and now won't turn back on. Head unit is good, because I can transplant it into another vehicle and it works fine. Checked all fuses both interior & main fuse blocks all good. One ting left is TNS relay, which I will replace today. Any other suggestions or ideas? This is for a '91 5 spd. Thanks in advance!