diff --git a/ltchiptool/soc/ambz2/flash.py b/ltchiptool/soc/ambz2/flash.py
index dee27df..b0c0e54 100644
--- a/ltchiptool/soc/ambz2/flash.py
+++ b/ltchiptool/soc/ambz2/flash.py
@@ -107,13 +107,17 @@ def flash_write_raw(
         self.flash_connect()
         assert self.amb
         callback.attach(data, limit=length)
-        self.amb.memory_write(
-            offset=offset,
-            stream=data,
-            use_flash=True,
-            hash_check=verify,
-        )
-        callback.detach(data)
+        try:
+            self.amb.memory_write(
+                offset=offset,
+                stream=data,
+                use_flash=True,
+                hash_check=verify,
+            )
+            callback.detach(data)
+        except Exception as e:
+            callback.detach(data)
+            raise e
 
     def flash_write_uf2(
         self,
diff --git a/ltchiptool/soc/ambz2/util/ambz2tool.py b/ltchiptool/soc/ambz2/util/ambz2tool.py
index 386a8b2..2c91bc5 100644
--- a/ltchiptool/soc/ambz2/util/ambz2tool.py
+++ b/ltchiptool/soc/ambz2/util/ambz2tool.py
@@ -13,7 +13,7 @@
 from xmodem import XMODEM
 
 from ltchiptool.util.intbin import align_down
-from ltchiptool.util.logging import LoggingHandler, verbose
+from ltchiptool.util.logging import LoggingHandler, stream, verbose
 from ltchiptool.util.misc import retry_catching, retry_generator
 
 _T_XmodemCB = Optional[Callable[[int, int, int], None]]
@@ -34,7 +34,7 @@ class AmbZ2FlashSpeed(IntEnum):
 
 
 class AmbZ2Tool:
-    crc_speed_bps: int = 2000000
+    crc_speed_bps: int = 1500000
     prev_timeout_list: List[float]
     flash_mode: AmbZ2FlashMode = None
     flash_speed: AmbZ2FlashSpeed = AmbZ2FlashSpeed.SINGLE
@@ -83,16 +83,16 @@ def command(self, cmd: str) -> None:
     def read(self, count: int = None) -> bytes:
         response = b""
         end = time() + self.read_timeout
-        end_nb = time() + 0.01  # not before
         while time() < end:
-            read = self.s.read_all()
+            if count:
+                read = self.s.read(count - len(response))
+            else:
+                read = self.s.read_all()
             response += read
             if count and len(response) >= count:
                 break
-            if not response or time() <= end_nb:
-                continue
-            if not read:
-                break
+            if read:
+                end = time() + self.read_timeout
 
         if not response:
             raise TimeoutError(f"Timeout in read({count}) - no data received")
@@ -100,7 +100,9 @@ def read(self, count: int = None) -> bytes:
             return response
         response = response[:count]
         if len(response) != count:
-            raise TimeoutError(f"Timeout in read({count}) - not enough data received")
+            raise TimeoutError(
+                f"Timeout in read({count}) - not enough data received ({len(response)})"
+            )
         return response
 
     def readlines(self) -> Generator[str, None, None]:
@@ -154,7 +156,7 @@ def ping(self) -> None:
         self.command("ping")
         resp = self.read(4)
         if resp != b"ping":
-            raise RuntimeError(f"incorrect ping response: {resp!r}")
+            raise RuntimeError(f"Incorrect ping response: {resp!r}")
 
     def disconnect(self) -> None:
         self.command("disc")
@@ -175,13 +177,16 @@ def change_baudrate(self, baudrate: int) -> None:
         self.ping()
         self.command(f"ucfg {baudrate} 0 0")
         # change Serial port baudrate
-        debug("-- UART: Changing port baudrate")
+        stream("-- UART: Changing port baudrate")
         self.s.baudrate = baudrate
         # wait up to 1 second for OK response
         self.push_timeout(1.0)
-        resp = self.read()
+        try:
+            resp = self.read()
+        except TimeoutError:
+            raise RuntimeError("Timed out while changing baud rate")
         if resp != b"OK":
-            raise RuntimeError(f"baud rate change not OK: {resp!r}")
+            raise RuntimeError(f"Baud rate change not OK: {resp!r}")
 
         self.pop_timeout()
         # link again to make sure it still works
diff --git a/ltchiptool/soc/interface.py b/ltchiptool/soc/interface.py
index 56b00ce..14a0ec1 100644
--- a/ltchiptool/soc/interface.py
+++ b/ltchiptool/soc/interface.py
@@ -141,7 +141,7 @@ def flash_get_chip_info_string(self) -> str:
 
     def flash_get_guide(self) -> List[Union[str, list]]:
         """Get a short textual guide for putting the chip in download mode."""
-        raise NotImplementedError()
+        return []  # Optional; do not fail here
 
     def flash_get_size(self) -> int:
         """Retrieve the flash size, in bytes."""
diff --git a/ltchiptool/util/streams.py b/ltchiptool/util/streams.py
index 0772bb9..328d9c2 100644
--- a/ltchiptool/util/streams.py
+++ b/ltchiptool/util/streams.py
@@ -110,7 +110,7 @@ def __init__(self):
         self.buf = {"-> RX": "", "<- TX": ""}
 
     def _print(self, data: bytes, msg: str):
-        if all(c in self.ASCII for c in data):
+        if data and all(c in self.ASCII for c in data):
             data = data.decode().replace("\r", "")
             while "\n" in data:
                 line, _, data = data.partition("\n")
@@ -118,12 +118,14 @@ def _print(self, data: bytes, msg: str):
                 self.buf[msg] = ""
                 if line:
                     stream(f"{msg}: '{line}'")
-            self.buf[msg] = data
+            self.buf[msg] += data
             return
 
         if self.buf[msg]:
             stream(f"{msg}: '{self.buf[msg]}'")
             self.buf[msg] = ""
+        if not data:
+            return
 
         if data.isascii():
             stream(f"{msg}: {data[0:128]}")
@@ -138,6 +140,7 @@ def on_after_read(self, data: bytes) -> Optional[bytes]:
         return None
 
     def on_before_write(self, data: bytes) -> Optional[bytes]:
+        self._print(b"", "-> RX")  # print leftover bytes
         self._print(data, "<- TX")
         return None