Check if the test leads are firmly connected with the unit.
If no, connect the test leads firmly to the tester.
Check if the test leads are firmly connected to the earth spikes.
If no, connect the test leads firmly to the earth spikes.
Check if the part where the earth spikes are stuck is enough moist.
If no, give enough water where the earth spikes are stuck.
Check the continuity of test leads.
If there is a break, replace the faulty test lead.
How to check: Set to the resistance range and short the test leads.