Can't upload ESPHome to US Plug "Upload buffer miscompare"

So I'm getting "Upload buffer miscompare" when I try and upload a ESPHome firmware to overwrite Tasmota. I suspect it's because it's got a 1M flash, but I'm using "esp01_1m" for the board. I'm basinc my configuration on https://www.athom.tech/forum/plugs/here-is-an-esphome-config-for-the-uk-power-plug, even pulled out the daily KWh usage stuff, to try and get the bin down smaller. Even though the original was still under 512KByte.

Anyone have any solution? Pull it open and flash over serial?

substitutions:
  devicename: deb_light_control
  upper_devicename: Athom Smart Plug
    # Higher value gives lower watt readout
  current_res: "0.00225"
  # Lower value gives lower voltage readout
  voltage_div: "757"

esphome:
  name: $devicename
  platform: ESP8266
  board: esp01_1m

wifi:
  ssid: "SSID"
  password: "SSID_PASSWORD"

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "${upper_devicename} Hotspot"
    password: "PASSWORD"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:
  password: "PASSWORD"
ota:
  password: "PASSWORD"

# Time used for daily KWh usage  
#time:
#  - platform: homeassistant
#    id: homeassistant_time

status_led:
  pin:
    number: GPIO0
    inverted: yes

binary_sensor:
    # Button 1 configuration
  - platform: gpio
    pin:
      number: GPIO3
      mode: INPUT_PULLUP
      inverted: True
    id: button_1
    on_press:
      then:
        - switch.toggle: relay_1
    on_click:
      min_length: 5000ms
      max_length: 10000ms
      then:
        - switch.turn_on: reset
  - platform: status
    name: "${upper_devicename} Status"

switch: # Set relays as switches
  - platform: gpio
    id: relay_1
    icon: mdi:power-socket-uk
    pin: GPIO14
    name: "${upper_devicename} Switch"
    on_turn_on:
    - switch.turn_on: sw_led1
    on_turn_off:
    - switch.turn_off: sw_led1
  # Register LED on GPIO
  - platform: gpio
    id: sw_led1
    pin: GPIO13
    inverted: True
  - platform: restart
    name: "${upper_devicename} Restart"
    id: reset

sensor:
  - platform: hlw8012
    sel_pin:
      number: GPIO12
      inverted: True
    cf_pin: GPIO04
    cf1_pin: GPIO5
    current_resistor: ${current_res}
    voltage_divider: ${voltage_div}
    current:
      name: "${upper_devicename} Amperage"
      unit_of_measurement: A
      accuracy_decimals: 3
      icon: mdi:flash-circle
    voltage:
      name: "${upper_devicename} Voltage"
      unit_of_measurement: V
      icon: mdi:flash-circle
    power:
      name: "${upper_devicename} Wattage"
      unit_of_measurement: W
      id: "${devicename}_Wattage"
      icon: mdi:flash-circle
    change_mode_every: 4
    update_interval: 10s
#  - platform: total_daily_energy
#    name: "${upper_devicename} Total Daily Energy"
#    power_id: "${devicename}_Wattage"
#    filters:
        # Multiplication factor from W to kW is 0.001
#        - multiply: 0.001
#    unit_of_measurement: kWh
#    icon: mdi:clock-alert
  - platform: uptime
    name: "${upper_devicename} Uptime"
    icon: mdi:clock-outline
  - platform: wifi_signal
    name: "${upper_devicename} Wifi Signal"
    update_interval: 60s