Many thanks to both replies.   
      
   I was leading to the conclusion that BLU shuts off USB OTG, for which I   
   needed to root. I switched on developer mode and the bootlogger switch. But   
   KingoRoot refused to root on grounds of 0x17ae78 error, and RootEssentials   
   showed no vold.fsab in etc, only a volte-cfg.xml.   
      
   I don't get to choose maufacturer or carrier, so am stuck with this BLU C5L   
   with Android 11 running on a reseller of T-mobile. My Prior phone was an   
   LG423 running on what appeared to be a GSM reseller of CDM Verizon.   
      
   --   
   	 Vasos Panagiotopoulos  panix.com/~vjp2/vasos.htm   
     ---{Nothing herein constitutes advice.  Everything fully disclaimed.}---   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)