VRSCURIOUS

Hello, my first post in many years having bought a very nice 2014 Fabia II Greenline 1.2tdi manual estate. Its on 86932 miles. Last weekend, we installed an Android Auto radio, using fuse 1 with a piggyback in order to create a switched ignition feed for the radio. Over the next day or so, my son was complaining of poor starting, bad idle and flashing orange glowplug light. Figured it might be battery related (sapped a lot of juice setting up the radio), so i charged it. No signs of excessive smoke or anything. This improved things a little but the glowplug light still flashes. However, attaching a modern bluetooth 5.2 obd2 reader and starting it having been left for a few days and it struggled a bit to start, the light was still flashing, even when warm it wouldn't rev past 3000 rpm and no fault codes could be found on either Car Scanner Pro or Torque apps. Any thoughts please? Was fuse 1 a bad idea? Is it likely a coincidence? Likely to actually be the glowplugs? (87k miles is typical life?) Many thanks! Jon