Can't flash 1 of 3 plugs (Deltaco SH-P01E, similar to Gosund SP1 et al)

Hello, I bought 3 Deltaco SH-P01E smart plugs, and have flashed two of them successfully using tuya-convert. But I'm unable to get the third one to work. When tuya-convert starts talking to the plug the blue led quickly stops flashing and tuya-convert keeps on "Resending SmartConfig Packets" until it gives up.

They were all bought together at the same store, so one would assume they're identical, but I see now that two of the boxes have "PO183437" printed on the bottom, but the third box has "PO184459" printed instead. I don't know which plug was in which box though. But maybe one plug is from a newer batch which can't be flashed?

For the record, I don't have the Deltaco app installed on my phone, so I didn't accidentally update the plug's official firmware or anything like that.

Logs:
[smarthack-psk.log](https://gist.github.com/abstrakct/4b3c5f7221eeb952d97c1602d004a699)

smarthack-udp.log:
```
Listening for Tuya broadcast on UDP 6666
Listening for encrypted Tuya broadcast on UDP 6667
```

smarthack-web.log:
```
Listening on 10.42.42.1:80
[I 200814 19:27:08 web:2250] 302 GET /generate_204 (10.42.42.11) 0.56ms
[I 200814 19:27:08 web:2250] 302 GET /generate_204 (10.42.42.11) 0.32ms
[I 200814 19:27:08 web:2250] 200 GET / (10.42.42.11) 0.51ms
```

smarthack-mqtt.log:
```
1597433210: mosquitto version 1.4.15 (build date Tue, 18 Jun 2019 11:42:22 -0300) starting
1597433210: Using default config.
1597433210: Opening ipv4 listen socket on port 1883.
1597433210: Opening ipv6 listen socket on port 1883.
^C1597433748: mosquitto version 1.4.15 terminating
```

[smarthack-wifi.log](https://gist.github.com/abstrakct/0b207450658573241157d0d814e08bb1)

For the plugs that I did successfully flash, here's the device-info from the backups tuya-convert made:
```
VTRUST-FLASH 1.5
(c) VTRUST GMBH https://www.vtrust.de/35c3/
READ FLASH: http://10.42.42.42/backup
ChipID: aa23d4
MAC: C4:4F:33:AA:23:D4
BootVersion: 7
BootMode: normal
FlashMode: 1M DOUT @ 40MHz
FlashChipId: 144051
FlashChipRealSize: 1024K
Active Userspace: user2 0x81000
```
I can provide the logs from the successful flashes as well if that's useful.

Any idea as to where the problem is? Is the third plug "unflashable", or is it possible tuya-convert will support it in the future? Let me know if there's any more info or logs I can provide.

Start by reviewing the linked smarthack-psk.log and smarthack-wifi.log, then compare them with logs from the two plugs that flashed successfully. No source file or test is named; the investigation is complete when it establishes whether the PO184459 plug is supported by tuya-convert or documents the missing information needed for support.

Written by the indexing model from the issue text.