Update bq Hephestos 2 probe offset

From #10234 by @thopiekar

Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h

  */
 #define X_PROBE_OFFSET_FROM_EXTRUDER 34  // X offset: -left  +right  [of the nozzle]
 #define Y_PROBE_OFFSET_FROM_EXTRUDER 15  // Y offset: -front +behind [the nozzle]
-#define Z_PROBE_OFFSET_FROM_EXTRUDER  0  // Z offset: -below +above  [the nozzle]
+#define Z_PROBE_OFFSET_FROM_EXTRUDER -4  // Z offset: -below +above  [the nozzle]
 
 // Certain types of probes need to stay away from edges
 #define MIN_PROBE_EDGE 10
 //#define Z_AFTER_PROBING          2 // Z position after probing is done
 
 // For M851 give a range for adjusting the Z probe offset
-#define Z_PROBE_OFFSET_RANGE_MIN -2
-#define Z_PROBE_OFFSET_RANGE_MAX  0
+#define Z_PROBE_OFFSET_RANGE_MIN -5.5
+#define Z_PROBE_OFFSET_RANGE_MAX -3
 
 // Enable the M48 repeatability test to test probe accuracy
 #define Z_MIN_PROBE_REPEATABILITY_TEST