Budget:20$,min of 5 yrs exp with BLE and services are needed with expertise.
1)You have to connect to last connected bluetooth and start service when sms is received with keyword.
Bluetooth connection code is also there ,you have to fix the flow by calling concerned methods in background so that connection will not be disrupted.
2)On connection with BLE and if you find speed is '0', and in unlocked state for 2 mins,you have to make it in lock mode ,locking function is already there,you can get all values by calling functions.
Call webservice(REST) after locking it,webservice code(retrofit) is also there,you have to call function.
3)Need to have bitbucket account and know how to pull and push code using git.
4)Small button need to be added in layout,matter of 10 mins
More tasks will be given after this,looking for long term and patience is needed during work
Estimate :2-3 hrs