otp: clearer message when device does not have current time for TOTP function

diff --git a/main/otpauth.c b/main/otpauth.c
index 18fb37e..d2120b3 100644
--- a/main/otpauth.c
+++ b/main/otpauth.c
@@ -217,7 +217,7 @@ void otp_set_explicit_value(otpauth_ctx_t* otp_ctx, const int64_t value)
     }
 }
 
-bool otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out)
+otp_err_t otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out)
 {
     JADE_ASSERT(otp_is_valid(otp_ctx));
 
@@ -227,14 +227,14 @@ bool otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out)
         value = time(NULL);
         if (value < MIN_ALLOWED_CURRENT_TIMESTAMP) {
             JADE_LOGE("Using TOTP without time set!");
-            return false;
+            return OTP_ERR_TOTP_TIME;
         }
     } else {
         // HOTP uses an incrementing counter held in storage
         value = storage_get_otp_hotp_counter(otp_ctx->name);
         if (!storage_set_otp_hotp_counter(otp_ctx->name, value + 1)) {
             JADE_LOGE("Failed to increment HOTP counter!");
-            return false;
+            return OTP_ERR_HOTP_COUNTER;
         }
     }
 
@@ -243,7 +243,7 @@ bool otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out)
     if (value_out) {
         *value_out = value;
     }
-    return true;
+    return OTP_ERR_OK;
 }
 
 static inline mbedtls_md_type_t get_md_type(const otpauth_ctx_t* otp_ctx)
diff --git a/main/otpauth.h b/main/otpauth.h
index 3ea4ece..86c0768 100644
--- a/main/otpauth.h
+++ b/main/otpauth.h
@@ -33,6 +33,8 @@ typedef struct otpauth_ctx {
     int8_t period;
 } otpauth_ctx_t;
 
+typedef enum { OTP_ERR_OK, OTP_ERR_TOTP_TIME, OTP_ERR_HOTP_COUNTER } otp_err_t;
+
 bool otp_is_valid(const otpauth_ctx_t* otp_ctx);
 
 // Parse the otp uri into a context object
@@ -40,7 +42,7 @@ bool otp_uri_to_ctx(const char* uri, size_t uri_len, otpauth_ctx_t* otp_ctx);
 
 // Update the context object with an explicit or default/calculated nonce value
 void otp_set_explicit_value(otpauth_ctx_t* otp_ctx, int64_t value);
-bool otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out);
+otp_err_t otp_set_default_value(otpauth_ctx_t* otp_ctx, uint64_t* value_out);
 
 // Get the auth code for the given context
 bool otp_get_auth_code(const otpauth_ctx_t* otp_ctx, char* token, size_t token_len);
diff --git a/main/process/dashboard.c b/main/process/dashboard.c
index 7835c45..5b8ee8a 100644
--- a/main/process/dashboard.c
+++ b/main/process/dashboard.c
@@ -1497,11 +1497,20 @@ static bool display_totp_screen(otpauth_ctx_t* otp_ctx, uint64_t epoch_value, ch
 
         // Update values
         if (auto_update) {
-            if (!otp_set_default_value(otp_ctx, &epoch_value)) {
-                const char* message[] = { "Failed to fetch", "time/counter!" };
-                await_error_activity(message, 2);
+            switch (otp_set_default_value(otp_ctx, &epoch_value)) {
+            case OTP_ERR_TOTP_TIME: {
+                const char* msg_totp[] = { "Failed to fetch time.", "Unlock with the", "Blockstream app." };
+                await_error_activity(msg_totp, 3);
+                return false;
+            }
+            case OTP_ERR_HOTP_COUNTER: {
+                const char* msg_hotp[] = { "Failed to fetch", "counter!" };
+                await_error_activity(msg_hotp, 2);
                 return false;
             }
+            case OTP_ERR_OK:
+                break;
+            }
             ctime_r((time_t*)&epoch_value, timestr);
             gui_update_text(txt_ts, timestr);
 
@@ -1572,11 +1581,20 @@ static bool show_otp_code(otpauth_ctx_t* otp_ctx)
 
     // Update context with current default 'moving' element
     uint64_t value = 0;
-    if (!otp_set_default_value(otp_ctx, &value)) {
-        const char* message[] = { "Failed to fetch", "time/counter!" };
-        await_error_activity(message, 2);
+    switch (otp_set_default_value(otp_ctx, &value)) {
+    case OTP_ERR_TOTP_TIME: {
+        const char* msg_totp[] = { "Failed to fetch time.", "Unlock with the", "Blockstream app." };
+        await_error_activity(msg_totp, 3);
+        return false;
+    }
+    case OTP_ERR_HOTP_COUNTER: {
+        const char* msg_hotp[] = { "Failed to fetch", "counter!" };
+        await_error_activity(msg_hotp, 2);
         return false;
     }
+    case OTP_ERR_OK:
+        break;
+    }
 
     // Calculate token
     char token[OTP_MAX_TOKEN_LEN];
diff --git a/main/process/get_otp_code.c b/main/process/get_otp_code.c
index 7968016..1bbae88 100644
--- a/main/process/get_otp_code.c
+++ b/main/process/get_otp_code.c
@@ -63,7 +63,7 @@ void get_otp_code_process(void* process_ptr)
 
     // Update the context with the current calculated counter value (derived from current time for TOTP)
     uint64_t value = 0;
-    if (!otp_set_default_value(&otp_ctx, &value)) {
+    if (otp_set_default_value(&otp_ctx, &value) != OTP_ERR_OK) {
         jade_process_reject_message(process, CBOR_RPC_INTERNAL_ERROR, "Failed to set OTP counter");
         goto cleanup;
     }