goodfet.monitor seems not working with facedancer21

[AlvinAlvin82]

I've flashed facedancer21 for the first time with this procedure:

1. cd goodfet/firmware
2. board=facedancer21 make clean reinstall

i've had a problem with pyserial: downolading the 2.7version

• pip install "pySerial>=2.0,<=2.9999"

I was able to flash the board.
After the flashing procedure i've tried this command board=facedancer21 goodfet.monitor test with bad feebacks

Performing monitor self-test.
Warning: waiting for serial read timed out (most likely).
Echo test failed.
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
ERROR Fetched 0154, 0302
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
ERROR, P1OUT not cleared.
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
Echo test failed.
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
ERROR Fetched 0100, 0302
Warning: waiting for serial read timed out (most likely).
Warning: waiting for serial read timed out (most likely).
ERROR, P1OUT not cleared.
..........

What's wrong with this procedure?

[AlvinAlvin82]

More info about my problem:

1. It is a random problem
2. I've bought a pre-assembled version (i don't think it is an hardware related problem)
3. I've obtained the following result with an strace

...
12:19:45 read(3, "\f", 1)               = 1
12:19:45 write(3, "\0", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\3", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\3", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\0", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "!\0\0", 3)           = 3
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 1 (in [3], left {tv_sec=11, tv_usec=984696})
12:19:45 read(3, "\0", 1)               = 1
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 1 (in [3], left {tv_sec=11, tv_usec=999998})
12:19:45 read(3, "\3", 1)               = 1
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 1 (in [3], left {tv_sec=11, tv_usec=999998})
12:19:45 read(3, "\1", 1)               = 1
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 1 (in [3], left {tv_sec=11, tv_usec=999998})
12:19:45 read(3, "\0", 1)               = 1
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 1 (in [3], left {tv_sec=11, tv_usec=999998})
12:19:45 read(3, "\0", 1)               = 1
12:19:45 write(3, "\0", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\2", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\2", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "\0", 1)              = 1
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 write(3, "!\0", 2)             = 2
12:19:45 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:45 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 0 (Timeout)
12:19:57 write(1, "Warning: waiting for serial read"..., 58) = 58
12:19:57 write(1, "ERROR, P1OUT not cleared.\n", 26) = 26
12:19:57 write(3, "\0", 1)              = 1
12:19:57 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:57 write(3, "\3", 1)              = 1
12:19:57 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:57 write(3, "\3", 1)              = 1
12:19:57 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:57 write(3, "\0", 1)              = 1
12:19:57 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:57 write(3, "!\0\1", 3)           = 3
12:19:57 select(4, [], [3], [], NULL)   = 1 (out [3])
12:19:57 select(4, [3], [], [], {tv_sec=12, tv_usec=0}) = 0 (Timeout)
12:20:09 write(1, "Warning: waiting for serial read"..., 58) = 58
12:20:09 write(3, "\0", 1)              = 1
...

4. I'm using the latest facedancer firmware version and Kali as OS