Is it possible to set more than one service ?

NRF.setServices({
  0x1809 : { // Health Thermometer
    0x2A6E: {  // Temperature
      readable: true,
      value : [1]
  }},
  0x180F : { // Battery Service
    0x2A19: {  // Battery Level
      readable: true,
      value : [1]
}}});

The above works for me - I think it's because you were trying to send a string inside an array as the temperature.

It should really have errored though - I'm not sure why it didn't