fix dfu with changes suggested by @enrikb

solo/cli/program.py

@@ -245,11 +245,12 @@ def enter_dfu(serial):
     """
 
     p = solo.client.find(serial)
-    p.enter_st_dfu()
-    # this doesn't really work yet ;)
-    # p.reboot()
-
-    print("Please powercycle the device (pull out, plug in again)")
+    try:
+        p.enter_st_dfu()
+        print("Please powercycle the device (pull out, plug in again)")
+    except Exception as e:
+        if "wrong channel" in str(e).lower():
+            print("Command wasn't accepted by Solo.  It must be in bootloader mode first and be a 'hacker' device.")
 
 
 aux.add_command(enter_dfu)

solo/devices/solo_v1.py

@@ -4,6 +4,7 @@
 import sys
 import tempfile
 import time
+from threading import Event
 
 from fido2.client import Fido2Client
 from fido2.ctap import CtapError
@@ -105,7 +106,13 @@ def use_hid(
     def send_only_hid(self, cmd, data):
         if not isinstance(data, bytes):
             data = struct.pack("%dB" % len(data), *[ord(x) for x in data])
-        self.dev._dev.InternalSend(0x80 | cmd, bytearray(data))
+
+        no_reply = Event()
+        no_reply.set()
+        try:
+            self.dev.call(0x80 | cmd, bytearray(data), no_reply)
+        except IOError:
+            pass
 
     def exchange_hid(self, cmd, addr=0, data=b"A" * 16):
         req = Client.format_request(cmd, addr, data)